Covenants says that a level 20 effect can grant a +1 to a lab score, any reason besides possibly breaking the system that you can't do a ring duration effect and get the same benefits?
e.g.: creo lignum base 5, ring, touch = lvl20
create light as bright as direct sunlight
would give the benefit of Magical Lighting: Lighting is provided magically. This Virtue functions as either Superior Lighting or Excessive Lighting (but without the space and Upkeep cost).
Superior Lighting: The lab is very well lit, so that things are easy to find, and books are easy to read, without eye-strain. +1 Upkeep, +1 Aesthetics; +1 Texts, +1 Im.
You could easily stretch your imagination and come up with several effects to get all the bonuses you want.
Is there a limit to the amount of bonus you can cram into a lab? something like no more than +1 quality or +1 specialization per lab size level?
And before it's argued you need to spend the time creating the spells, effectively using a season to "pay" for improvements, there is nothing stopping me from taking 5 mins to draw a circle and then sponting a level 20 effect
Well, yeah, "breaking the system" would be the big one.
Serf's parma, but I recall language in Covenants that might have been trying to rule out what you're suggesting. I think it was something about how it was assumed that a magus would normally be casting any spells on his laboratory that would benefit his season's work.
Also, the durability of the ring might be an issue - a ring that you spent five minutes drawing on the ground with chalk is going to be pretty easy for a careless footstep to efface.
I think that the spell you want is precisely how you get the effects of magical or superior lighting, but that they still take up space in the lab. Many lab features don't seem to really take up physical space in the lab; I take it that the "size" limits on labs are really a game balancing mechanism.
From page 122 of Covenants, each spell adds a point of warping score, also a spel can not give a bonus to a lab specilization containing an art that was used in a spell. (The character is already assumed to be using this art to cast spells in the laboratory and the spell bonuses are assumed to be included in the lab total through his art score). Spells can also not be used to raise general quality.
I'd gone back and re-read that part... It deals with repeatedly casting a spell for an effect. I can understand the warping. Essentially each time you cast it will be slightly different allowing "flaws" to creep into your work due to the variation.
By using "ring" or, if you have access to it, "until" you are only casting once. Whats the difference from me casting a variation of lamp with out flame once Vs an item that cast it and maintains concentration?
Why should an item give me a bonus when it cast something I can easily cast?
Over all it seems like a cheep fix that was tossed in at the end to attempt to save the system of lab improvements.
The more I think about it the more I lean towards scrapping the whole idea of lab specilizations/improvements
If it doesn't float your boat, don't use it but I think it adds another really nice dimension to lab work. Now I can either improve my arts over a season or I can add work on my lab and give myself a broader bonus.
There are some things you can, as a player, just accept as game balancing while finding your own logic as to why the rules are as they are. Why is it safer/better to use an item rather than keep casting a spell? Because sometimes the magus forgets and spoils what it was he was doing? Because of fluctuations in the magical ambience that wouldn't happen through item use? Pick one or make a new one up.
As to the other options you mentioned, Ring/Until, well either let 'em have it or simply rule that it doesn't matter and a spell's a spell.
The rules cannot possibly hope to model each and every situation. As players we have to find a way through that suits our needs. Personally, I'm looking forward to expanding my lab (when the council deigns to hand over the old barracks to me...).
I like the lab rules. I like the idiosyncratic labs they create. Now each magus' lab is a different magical place rather than an undescribed room. Magi have cause to set up lab on a clifftop, below the sea, or so on. It's interesting.
I agree with marklawford, sometimes you just accept that the rules are the rules and flow with it. I'd just excuse the different effects spells and magic items have as artifacts of the subtle differences between the two methods of working magic, and let it be ("fluctuations in the magical ambience" indeed).
One aspect I'm not too keen on regarding lab specialization rules is that installing an item adds the respective benefits in no time. I'd house rule it to taking the same time as installing a comparabe Virtue, but the time taken to manufacture the item counted.