The wizard doesn't have scarce spell slots. That's my whole argument.
5e casters are designed to have enough spell slots that over 35 rounds of casting, the noncasters catch up. That's too many rounds for anything but a moderate sized dungeon.
Changing rests doesn't fix the problem because you still need 35 rounds of offense between the rests. 8 hour long rest. 1 week long rest. The game still mandates 35 rounds of offensive combat to drain the casters to average the noncaster.
The 35 rounds of offense seems quite a lot. Based on my calculations in the first Post in this thread, at 18 rounds a Fighter and Wizard are somewhat equal. With 36 rounds, the fighter will do twice the damage a wizard will do, if the wizard would use all his Spell slots to do use the highest single round damaging spells.
Like, on Level 1 a Wizard has 2 (with arcane recovery) 3 attacks in between Long Rest where he will do on average more damage than a fighter in a round of offense. After that he is reduced to his cantrips and the fighter will out damage him.
On Level 5 a Wizard has will do even with his highest spellslots on average less single target damage than a fighter. Only with AOE Spells will he do more damage to multiple Targets than a fighter could (on average).
On Level 10 a Wizard can do more single target damage with his two highest spell slot categories, so 6 Spell (3 level 5 and 3 level 4 spells) than a Fighter (on average). After that he is behind on single target damage.
At Level 15, his level 7, 6 and 5 Spellslots will do more single target damage. That are 5 Spellslots. After that he will be again behind the single target damage of the Fighter.
At Level 20, only his Level 8 and 9 Spell slots (2 Slots) will out damage on average the fighter on single target damage. After that he will fall behind.
Thats what also my Post shows with which I started this thread:
With a single Target, Fighter and Wizard are equally good even with only 9 Battle Rounds. And with multiple enemies in one battle, you are good with 18 battle rounds.
Because for battle, actually only the highest spell slots count for dealing damage, or they get ineffective.
At the higher Levels (11+), Cantrips replace Level 1 (and from Level 17 on) Level 2 spells as Damage dealing spells.
So a Wizard has actually only 3 to 6 Spellslots with which he can do more damage than a fighter on any levels. If we account for arcane recovery, he has 1 to 2 more spellslots that will out damage a fighter.
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But I agree on one thing:
Changing just the duration of how long it takes to get the benefits of a long rest will not change much, if you just get 100% resource recovery.
The big problem is the 100% recovery, no matter the amount of resources you had before the rest.
Because it really doesn't matter if you have an all fighter or all wizard party: When they just rest after every fight and get a 100% HP and Spellslots after each rest, the encounter math breaks down. You would need at least double deadly encounters according to the DMG to be a meaningful challenge.
The next big issue is, that against a single target, Wizard and Fighter are very well-balanced unless you really go down to one fight (three battle rounds) between long rests.
But except for creatures with legendary actions and lair actions, fights against a single monster are not the norm.
I think 4e did that better. They assumed a standard fight would be 1 Character vs. 1 Monster and balanced accordingly.
5e is balance 4 vs. 1 and breaks quickly down when you have 4 vs. 2 or 4 vs. 4, especially when you follow the DMG guidelines and making 4 vs. 4 fights even easier.
My whole caculations of Fighter vs. Wizard started, because I'm building my own Monster Creator, that I tried to based on a 1 vs 1. Thats why I calculated the Fighter and Wizard damage Output in the first place (and use the average between these two as a basis for my Monster Creator).
And I think it works okay so far. When I put in that I want 1 Monster vs 4 Characters (Boss Monster) I come close to the DMG 5e Quick Monster Stats for Creating Monsters.
It also tells me more about these quick stat assumptions.
Like according to the DMG, a CR 1 Monster has between 71 and 85 HP, 13 AC, +3 to attack and deals on average 9 to 14 damage on a hit.
In order to get that stats in with my monster creator, I had to wiggle a litte. According to my creater, such a monster would be a hard encounter. It would on average take 4 characters 4 rounds to defeat that monster and the damage output of 9 would be hard, of 14 would be more than deadly.
What I found, if I go by CR = one creature of that Level vs a Party of 4 of that Level, that at the first levels, the battle will be around 4 rounds and hard to deadly, at higher levels it will be easy and two rounds of battle if I follow the DMG Creature Creation Guidelines.