The power level of a daily caster is directly proportional to how many combats the party is expected to face between rests, and that number changes depending on the group and the DM. So sure, you can toss random encounters at the group and they'll learn to stretch out their spells over 3-4 encounters. But Bob down the street is letting his casters blow their loads and rest every encounter. And Gary in Ohio won't let his players rest until they've gotten through 6-8 encounters.
So the PROBLEM is that in each of these groups, the wizard's power level is vastly different. Bob's wizard is overpowered, your wizard is probably appropriate to the character level, and Gary's is underpowered.
So either you have to tell Bob and Gary that they're doing it wrong (badwrongfun), or you have to adjust the game mechanics to encourage (or force) casters to spread out their spells an appropriate amount.
Um, if Bob is happy letting his party rest after every encounter, he can continue to do so. Obviously, he's not bothered by Novas if that is what he is allowing. If he is, he can follow my advice form above. And, if Gary isn't "letting" his players rest... yeah, he's a DM that needs help and he's likely to find out when his players keep dying and tell him his game isn't fun for them. Again, the problem will work itself out.