Stacking extra attack

[GeneralVryth]

This is exactly why I would prefer if most/all powers were on a short rest or even encounter-based recovery. 1) character power is more predictable for the DM as characters would almost always have their abilities ready, and 2) it better reflects, as you note, the reality of physical feats of prowess. Maybe not repeatable every round, but certainly repeatable as soon as the fighter gets a breather. I would bring magic in-line with this for reason 1 and for 3) the classes would be better balanced

You know there was a D&D edition that did what you describe. 4e, and my understanding is 5e has solidly trounced it in terms of popularity. It's possible when designing games in general to be too balanced, and the D&D player base has straight up proven it's okay with or prefers a level of imbalance if it means they get more variety with their characters. So the trick becomes creating that variety while keeping it as balanced as possible and not breaking verisimilitude too badly. Which brings me back to my chart from before and the question about long rest, non-magical resources. The only ones I can think would be more narrative focused like calling in a favor, or some kind of Schrodinger's tool that a character picked up in the past and it becomes what it needs to be now. I am not sure either of those work that great.

So that brings us back to trying to modify things so the short/long rest balance is better, both in the classes and DM guidance. Sorcerers using Spell Points on a short rest is easy (I keep thinking they should be Spell Points in general, I never thought much about the rest cycle). I suggested a Warlock-like Druid class (and provided an example starting point in another thread). Converting 1 of the Ranger, Paladin, and Artificer to some kind of short rest alternative to their spell slots would be ideal, but I am not sure which one would work best, and that may be the most involved conversion.

I really don't understand what you're getting at with this. You're comparing existing rules to theoretical rules (that aren't even representative of a common homebrew AFAIK). Martials get nothing from multiclassing in terms of stacking. Casters get something. You saying "well they should be getting more*" is entirely beside the point.

It's not theoretical rules. It's assessing the value of something by comparing the cases with and without it. It would be like comparing a Fighter class without the Extra Attack progression to the standard Fight class to see how much difference the Extra Attack progression makes on its damage. The spellcasting multi-class changes what you get when multi-classing into a full caster. The nature of that change as a buff, nerf, or something else is informative. You clearly see it as a buff, hence why you think casters get some special positive treatment.

*is it actually more??? Let's see!

[shrinking progression for space]

Yeah I stand by what I said...I'd rather continue the base progression of casting than "restart", except maybe with very specialized builds. I'm not seeing an obvious place where restarting would be beneficial. At level 12, where nothing is gained? Sure, that specific level is better to get 2 1st level slots. But I'd rather get the 7th level slot at 13 than the extra 1st level slots. Why? At that level, I have plenty of slots. I'm not worried about running out of utility slots. And the option to upcast certain things is pretty nice. And worst comes to worst? I upcast my silvery barbs or counterspell or whatever out of a very high level slot.

Is continual progression making wizard 11 cleric 5 worse? Nominally, yes. Spells known are the same. In current system, that character has 18 spell slots going up to 8th level. In your system, they'd have 25 slots but up to 6th level. But 18 spell slots is 18 spell slots - plenty of spell slots!! Getting more of a resources you already have a ton of bumps into marginal improvement.

You may be right the multi-classing rules on spellcasting on average are more of a net buff than nerf. I am still on the fence, but's not as clear cut as I thought. The locked in ability to share spell slots is definitely a buff though. That's what makes Sorcadins really possible. Which makes me wonder if there is something to the reverse of this thread title. What if Extra attack still didn't stack (though it did have some alternative bonus if you had more than 1 instance), and spell casters didn't have a shared slot progression? By that I mean each caster has its own spell slots and those can't be used to fuel the abilities of another class. Warlock Pact slots also wouldn't be usable to fuel the spells or abilities of another class. It would probably be a bit of a housekeeping for PCs that were built as dual fullcasters, but it might make multi-classing more balanced in general, and it would certainly be more consistent. Something may still need to be done with the 1st 1 to 3 levels of class being more valuable on average encouraging dips.