5e was designed around ending sessions with your resources not at 100%.No way in hell. You cannot fit 6-8 fights in four hours even though that's all you'd do. And I want majority of the game time to spent to other things regardless. Two fights per four hour session is pretty much the max, maybe three if they are really simple ones, but I wouldn't make a habit of it. And zero to one fights is pretty normal.
Every single edition was designed for you to end with your PCs incomplete unless you were running Gygaxian Hubtowns .
That's is why Vancian magic was chosen. Because you were supposed to literally erase expended spells so you didn't have to worry about what was spent. It was erased gone
But when 5e turned everything numerical, you suddenly had to manage a ton of numbers and everyone wanted to start sessions fresh rather than recalling why you where at 2/4 first level spells.