What originally got this discussion going was reading of Renegade's Wizard Spellbook, Volume I, page 34, by Mongoose Publishing. In regards to learning certain spells – which they term Archaic Spells – their rules require one week of study per spell level. Each additional week of study will provide a +1 to the chance to learn the spell.
Now, to me, this seems excessive. How do you role play such a thing? There's no way to do it without causing disruption to the game's rhythm. Even if you allow the time for study to take place between gaming sessions, what did your other players "do" during the 10 weeks your Wizard researched that 9th level spell?
I believe that one day of study, per spell level, is perfectly sufficient. After this, each additional day spent studying the spell can add a +1 to the Wizard's chance of learning the spell. This is a reasonable amount of time between gaming sessions. A week to ten days gives the other characters time to relax, shop, trade, repair equipment, brew potions, scribe scrolls, etc. But any time period longer than that simply disrupts the game's tempo.
I also believe that "Manna Pools" and "Spell Points" are disruptive to the game. In our discussion on Canonfire! various DMs who use these "home brew" systems talk of how they – along with letting their Wizards cast spells as though they were Sorcerers – can grant Magic Users enormous power, even pointing out that under such systems a Wizard could cast a dozen or more Lightning Bolts in a single day. That is a potent Wizard. But turning around and talking about how Wizards can "take over" the game, dominating it, seems a contradiction. And so I point out: That's exactly why the system was constructed the way it was.
We turn to 3.5 Edition's Player's Handbook, to point out the differences between Sorcerers and Wizards. It is clear to see that Wizards are more versatile than Sorcerers, but not necessarily more powerful, as some think. At 6th level, a Sorcerer can cast three 3rd level spells per day; that's three Fireballs. (Page 52, Table 3-16: The Sorcerer) The Wizard can only cast two 3rd levels spells a day, but, does he memorize two Fireballs, or only one? (Page 55, Table 3-18: The Wizard)
The versatility comes into play in that the Sorcerer – at 6th level – can only "know" one 3rd level spell. Does he choose Fireball? (Page 54, Table 3-17: Sorcerer Spells Known) The 6th level Wizard, on the other hand, has no limit on how many 3rd level spells he can "know." There's only a limit on how many he can memorize for the day. Now, granted, 2nd Edition's Player's Handbook, page 16, Table 4: Intelligence, does limit the number of spells – per level – a Wizard can know, based upon his Intelligence, but we've already discussed that and I've stated that I disagree with that limitation. For me, "knowing" means having the spell written in a spell-book in your library and since there is no limit on the number of books a Wizard can read, why should there be a limit on the number of spells a Wizard can "know?"
This, then, is the tried a true method of keeping a Wizard's power in check. Creating Manna Pool and Spell Point systems also creates the need to come up with additional "Home Rules" to keep the Wizard's power in check so that he doesn't come to dominate the game. It is simply creating too much work for the DM. If your player wants versatility, then he/she should be a Wizard. If, on the other hand, your player wishes to "toss about" whatever spell he/she is in the mood for at that particular moment, then they need to play a Sorcerer – and accept the limitations that go with it. All limitations set in the various Editions are created for the sole purpose of not letting the Magic User dominate the game to the point where all other player characters become redundant, little more than props.
One commenter in our discussion on Canonfire! posted: "The main reason was one of frustration with how rigidly affixed spells were aligned. Oftentimes, my wizard (or cleric) would only need a 'lesser' spell (such as Light) but, according to the rules, if you were out of 1st level spells, you couldn't do it, even if your 2nd, 3rd level, etc. spells were not expended. I didn't like how casters were 'pigeon-holed' in this manner."
And yet, this is exactly how the power of Wizards is "checked," keeping the game in balance, even when your Wizard reaches higher levels. As I've said, creating the Manna Pool, or Spell Point system, merely enhances the Wizard's ability to dominate the party and game, facilitating the creation of even more "House Rules."
Of course, one simple "fix" is that the Guidelines do allow the Wizard to load his higher level spell slots with lower level spells! If your Wizard feels that he/she may find themselves in need of an "extra" Light spell, simply put a 1st level Light spell into a 2nd level slot! Ah, the versatility of the Wizard is an astonishing thing. LOL
Your Wizard must choose the spells he/she feels he/she will need during the course of the day. Why load a 2nd level spell slot with a 2nd level spell he/she feels might not be necessary? Skip the unnecessary 2nd level spell in favor of the much more needed 1st level spell.
The ways of limiting the "over-powering" Wizard are numerous, without having to resort to a bunch of "House Rules." The same thing can be said for increasing the versatility of the Wizard. There's no need to turn your Wizard into a Sorcerer. In using these systems, you greatly increase the power of your Wizard, making it much more likely that he/she will take over the game. You've also supplied your players with an excellent reason for not playing a Sorcerer. After all, the Wizard can do exactly what the Sorcerer can do; only the Wizard is a lot more powerful.
Well, I'll stop for now. I'm quite sure that we are by no means finished discussing Wizards and their limitations and abilities. See you next time!