Is there anything stopping you from creating a series of charged items at concentration duration and a (lesser or greater) enchanted item with a structure target maintain the demanding spell to create a series of permanent enchantments? For example:
Pipe of endless warm baths
A terracotta section of pipe enchanted as a charged item with a single charge of the following effect:
Base 4(heat an object enough to boil water) +0personal +1conc +0ind
Total: crig5
The demanding lamp
A brass lamp enchanted as a charged item with a single charge of the following effect:
Base 5(create daylight) +0personal +1conc +0ind
Total: crig10
Rustling curtains of drafty warmth
A set of rough linden curtains enchanted as a charged item with a single charge of the following effect:
Base 2(make breeze that is warm to the touch) +1touch +1conc +0ind | +1auram
Total: crig(au)5
&c
Plus:
Mallet that maintains the maddening myriad
This wooden mallet is enchanted as a lesser enchanted item with the following effect(i didnt work out shape and material boni or vis capacity or anything i just gave it a silly name):
Base 4(sustain a spell up to level 10) +1touch +2sun +3structure | +4continuous
Total: revi34
I suppose part of the answer is that at least some of the charged items could be replaced with (potentially sponted) spells maintained by that same lesser item
If we consider that an at least moderately experienced magus can probably spont most things up to level 15 outside of their specialty, eventually (5 in all arts, roll an 8(slighly better than 1in5), aura 3, stamina 1, at least some skill in artes liberales and philosophie and a couple points of floating bonuses), it's still worth using charged items for spells of 4th magnitude or higher for this kind of scheme(of course you're going to need a stronger mallet for that)
So effects like:
Base4(+9 on recovery rolls) +1touch +1conc +2room
Total: cran20
Base10(create a geyser with a very high flow rate) +1touch +1conc
Total:craq20
Base4(ward against normal rain) +1touch +1conc +2room
Total: reau20
Base4(+9 on recovery rolls) +1touch +1conc +2room
Total: crco20
Base10(create +15dmg fire) +1touch +1conc
Total crig20
Base4(block intellego magic of level 5 or less) +1touch +1conc +2room
Total: crvi20
Note: this spell spell blocks fingers for eyes
Base5(block intellego magic of level 10 or less) +1touch +1conc +2room
Total: crvi25
Note: this spell blocks convergence of birth
Base5(provide false information to intelligo magic of level 5 or less) +1touch +1conc +2room
Total: crvi25
Note: this spell deceives fingers for eyes
Base15(provide false information to intelligo magic of level 10 or less) +1touch +1conc +2room
Total: crvi35
Note: this spell deceives convergence of birth
Of course you'll note that none of the effects I mentioned use muvi
Sorry for being a little snippy, it's kind of annoying to always get this response to posts that are very explicitly not making use of muto vim effects
All of the charged items using concentration as the duration need to add +5 levels to the effect so that the item maintains concentration. Otherwise the effect will be functionally momentary, as no-one and nothing is concentrating on the spell.
Concentration: When investing an effect, you can arrange to have the device maintain concentration on the effect for the wielder. This option adds +5 to the effect’s level. Note that the wielder still needs to concentrate to change how the effect is used. For instance, a levitation belt that does not require concentration can hold someone in the air, but to move up or down the wielder must concentrate. Effects left to their own concentration start to wear off at sunset and sunrise. At these times the wielder must concentrate on the effect for a few moments to perpetuate it until the next sunrise or sunset, whichever comes first. (p. 99)
You might better off adding 9 to the effect (+1 magnitude to raise duration to sun, +1 for 2/day, +3 for environmental trigger) for a genuinely always on item. Only adds 4 to the effect over device maintains concentration, and avoids to nuisance of the wielder to concentrate on each item every single sunset and sunrise.
Honestly, on reflection I don't know how the typical sun duration/2 uses/environmental trigger would work with a charged item, which only gets one use. But maintaining concentration would be impossible for anything other than an item you carry with you at all times, and a careful attention to the time of sunrise and sunset.
Which is why I instead abuse circle/ring effects for my munchkinism. I only need to spend a season once per item type, to learn the effect as a formulaic spell. (As I advance, I may be able to spont many of the easier effects, saving even more time.) If some inconsiderate monster breaks my circle and ends my effect, I can just cast again when I have a chance. (By preference, I put the spell on a stone disk, then use a variant of Hardness of Adamantine to make the stone mostly unbreakable and Object is Stubborn to stick it to where it needs to go, all using the same circle along the side of the disk. A light, cooler, or heater will still affect the local area outside the circle. If I'm feeling fancy I also add a simple creo imaginem effect to give the disk a light glow of an appropriate color, so you can tell at a glance if the circle is still intact. If hearing it fall off the wall wasn't enough of a clue.)
For really critical effects, yes, I usually go with a lesser enchantment. Sometimes reliable is more important than cheap. A Verditius would spend seasons to enchant the entire room with an elegant array of effects, but my characters mostly want to quickly accomplish some simple task and then go back to what they were doing.
Even better would be to replace those "charged items" with spells. Several of those listed can, in fact, be cast spontaneously without fatigue (and thus without any risk of botching) by a magus of some experience. Even those that cannot, can be easily learnt as formulaic spells with "leftover" points from other spell research.
And for a circular structure (and/or rooms, objects etc.) consider the possibility of replacing the "mallet" with a D:Ring Maintain the Demanding Spell, learnt as a formulaic. It's used in extensively in our sagas. Some examples of what can accomplished - and the savings for a thrifty covenant - can be found here. You are encouraged to add your own (remember to provide not only the spell, but a rough analysis of how much you'd expect in savings)!
True, but magi don't want to be casting divide by 2 sponts daily. The stamina is irrelevant. Rest 2 minutes, stamina returned. What matters is all divide by 2 sponts are a stress die. Any stamina spont cast daily means on average 3.65 botches a year, so 3.65 twilight points.
Non stress die sponts of anything over magnitude 1 is the province of the specialist, so charged items are great for anything over magnitude 1 you intend to be used daily.
This was the main question I had in the thread actually. My understanding is that constant effect devices don't flicker even a hair, so they should be fine to bridge a single charged item(or spell) across sunset/sunrise.
There was also a little bit about sequencing/manipulating concentration lapse/sun duration at dawn/dusk to achieve specific goals which didn't make it in I guess
My understanding of the constant effect devices is that they achieve their effect due to the overlapping expire time at the sunset/sunrise. The sunset/sunrise is not a single instant, but a timespan, during which the spell/effect is still active, and during which the environmental trigger activates, spending (for a lesser enchantment or invested device) one of its usage per day.
In case of a charged device it's one of the charges that is expended, therefore limiting its usage to a few days, depending of the maximum of the charges available. Basically to achieve the effect 2 charges per day must be spent.
Yes well, in the, extensively drtailed, example provided in the op, the charged items, or spells, are being sustained by a constant effect device, rather than being constant effect themselves.
Anyway, I've basically got my answer at this point anyway
I think the main argument against this is that there's no easy way to discriminate between maintaining effects cast by an item and other types of effects, or between effects you wish to maintain and effects you don't want to maintain, short of magic resistance preventing maintaining every personal effects cast on a magi within the structure. Bind wound on a grog? The grog can't heal until he's out of the structure. Your apprentice created an illusion for a practical joke? The illusion stays there until you dispel it. Almost everyone within the structure, and the building itself, will start warping at an incredible speed.
I only need to spend a season once per item type, to learn the effect as a formulaic spell. (As I advance, I may be able to spont many of the easier effects, saving even more time.) If some inconsiderate monster breaks my circle and ends my effect, I can just cast again when I have a chance. (By preference, I put the spell on a stone disk, then use a variant of Hardness of Adamantine to make the stone mostly unbreakable and Object is Stubborn to stick it to where it needs to go, all using the same circle along the side of the disk. A light, cooler, or heater will still affect the local area outside the circle. If I'm feeling fancy I also add a simple creo imaginem effect to give the disk a light glow of an appropriate color, so you can tell at a glance if the circle is still intact. If hearing it fall off the wall wasn't enough of a clue.)