Baby Samurai said:
Not even, but I'm curious as to why you would think so.
What happens with 5 encounters? 6? 7? 8?
With your house rule, the DM could STILL:
dare to throw one too many encounters at them that day
and the player could still be out of PP or spells in a latter encounter. This can especially be true for a dungeon crawl.
All your house rule does is hinder a Psion and a Sorcerer. And it crushes a Bard who now becomes a backup fighter with virtually no spell casting. It prevents them from using up too much PP or spells too early as long as there are only 4 encounters. It is totally debatable as to whether this is a mistake on the part of the player to do so (without the house rule). If the first encounter of the day is the mega-encounter at the end of an adventure sequence against the BBEG and his henchmen, the psion or sorcerer (or another team member) could be screwed.
PC 1: "Why didn't you help against the BBEG?"
PC 2: "I did. I manifested an augmented Force Shield, but then I was out of power points. Besides, I didn't die. Only the Cleric and Rogue died."
And, if there are more than 4 encounters, a Psion could still use up too much PP with your house rule.
The problem you are fixing with your house rule is not a game mechanics problem. It is a decision making issue for players.
No different than a Rogue deciding to not check for traps this time and having one blow up in his face because he did not bother to look for it.
The problem is all in your head, it is not in the game mechanics.
Encounter 1 for 10th level PCs:
PC Leader: "Sorcerer and Wizard, how many 5th level spells can you cast?"
Wizard: "3"
Sorcerer: "1"
PC Leader: "How many 4th level spells can you cast?"
Wizard: "4"
Sorcerer: "2"
PC Leader: "Ok, the Wizard takes on the BBEG and the Sorcerer, see if you can take out a henchmen or two."
It's practically as if the Wizard is two or more levels higher than the Sorcerer with regard to durability per encounter.
All you've done here is make the Wizard the Nova high level spell caster and nerfed the Sorcerer into a support role. You've taken away one of the significant advantages that a Sorcerer has over a Wizard (more spells available at each level) and totally changed both class balance and group dynamics by doing so.
On the surface, your house rule sounds reasonable, but it really horks up game balance. Most people consider Sorcerers and Bards already on the low end of the class balance scale, but your nerf bat takes them totally out of viable contention.
In our games, there are sometimes extremely challenging mega-encounters that use up nearly all of the party resources and those could not exist using your house rule without major modification or TPK.