I had been iffy when this was brought up a while ago. It came to mind when rereading some parts of ArM5. I think the sample power Speech on page 105 of ArM5 might shed some light on this.
If constant effects are possible, this statement is not true. This is because the duration would not "need" to be Concentration. It could be constant, set with D: Sun, environmental trigger, and 2 uses/day. Thus this implies constant effects cannot be put in the familiar bond. Do we have anything in canon that disagrees with this statement in ArM5?
Alhough if the bond maintains concentration, the effect is pretty constant.
Yes, but if you have something like 10 effects, there becomes a big difference at sunrise/sunset. Concentrating on 10 at once to keep them all active is pretty difficult. Also, it most likely matters if you enter a foreign Aegis. Unless we're giving an Aegis powers of a disenchanting ritual, constant stuff is safe. But D: Concentration stuff will likely fail and have to be redone. Similarly, taking it down via Perdo Vim is different. Mostly this would only matter for a Wizards' War, but still...
On the other hand, an ArM5 p.99 box constant effect in a familiar bond - if allowed - would be in most respects for the life of both maga and familiar. A maga could just leave a normal enchanted device in the lab and thus get rid of its constant effect on herself. But she would have to tamper with the familiar bond to free herself from constant effects in it - with verrry serious consequences.
So it is IMO beneficial to a campaign and its characters, to read
(underscores mine) most literally, and to require that familiar and maga be able to switch off all the bond powers on each other. And this indeed excludes ArM5 p.99 box constant effects in the bond - unless such an effect affects both maga and familiar. Yadda yadda, we went through that before.
And if a player jumps through that hoop just to get an ArM5 p.99 box constant effect in the bond, the troupe can let his maga prance onward towards her doom. I indeed cannot imagine a single such continuous magical effect on maga and familiar without a situation, where she would need or strongly desire to take it off.