Psion said:
I think that's when I began to realize that the Vancian-style system wasn't so bad. In many ways, it was very clever and very well suited for gaming. Most people never realize it, though, because it has always been there for most gamers.
I'll be the first to admit that the Vancian-type system is very well suited for gaming. Its advantages are:
1. Every spell is a discrete, reasonably well defined (of course, there are exceptions

) effect, so it is usually quite clear what the spell does, and there is no element of putting the spell together from a variety of base effects on the fly. This speeds up spell resolution.
2. Less in-game tracking. Unlike spell point or fatigue systems, a player only needs to keep track of what spells he has left.
The major difference between a per day system and a per encounter system is how often your spells refresh, not the base characteristics of the Vancian system itself - whether a wizard spends an hour at the start of each day to prepare his full complement of 24 spells, or whether he spends fifteen minutes after each encounter to refresh his six spell slots.
In fact, from the perspective of point 2 (less in-game tracking) a per-encounter system requires less book-keeping on the part of the player.
Of course, there are some effects that may get out of hand under a per encounter system, but these can be managed by placing additional restrictions, e.g. longer casting times, time of day requirements, location requirements, xp/gp/action point costs, changing the effects of the spells, maybe even an explicit number of times per day restriction.
It seems to me that it would be better for the problem spells to balance themselves than to remain with a per day balance just to accomodate them. And, as mentioned, if you want to retain a per day balance, you can just multiply per encounter resources by the average number of encounters per day.