You're not supposed to long rest after every battle, you're supposed to use a lot of cantrips and try to save your spells for moments when they're needed, like potions. Or in the case of Warlocks, you regain spells on a short rest. Also Circle of the Land Druids do too. Sorcerers rarely run out of spells at higher levels, but the trade off is that they get fewer spells, so if you want to cast all of the time in combat you want a sorcerer who has a pile of nearly-always-good spells like Magic Missile, Chromatic Orb, Fireball, etc.