If you haven't looked at it, I recommend this thread I started the other day-
How to easily balance all the short rest classes.
Anyway, the gist of it was that any short rest resource could be converted into a long rest resource by multiplying it by 3. So, for example, if a Warlock has two "short rest" spells, then they should have 6 spells per day. If a monk has 4 ki, then they should have 12 ki per day. And so on. The point of this was to help balance the "short rest" classes with the "long rest" classes, especially when it came to tables that didn't allow for short rests at the usual interval (2 shorts per long- if it was 3 shorts per long, then it would be 4x, and that gets a little much).
But some of the comments in the thread made me think about this issues in a little more depth. I've always taken it as a given that there are short rest classes and long rest classes, but I've never really teased out that thought, or what it meant. So let's start with the basic analysis- what is a short rest class, and why does it matter?
Traditionally, most people would break classes down as follows in terms of the rest abilities-
Short Rest
These are the classes that have abilities that primarily key on short rests.
Fighter, Monks, Warlocks
In the Middle
These are the classes that are primarily long rest, but have some short rest abilities.
Bards, Clerics, Druids, Paladins, Wizards
Long Rest
These are the classes that are almost solely long rest.
Artificers, Barbarians, Rangers, Sorcerers
Rests aren't the Boss of Me
Rogues
So when you look at this, and you're trying to see which classes have a short rest
problem, something becomes quickly apparent. There are only three classes that you can even classify as short-rest dependent.
Of those three classes, one of them is the Fighter. Now, don't get me wrong ... short rests are REALLY NICE for the fighter. The base fighter abilities, like Action Surge and Second Wind ... yeah, short rest. And if you go battlemaster, you want those short rests. But the thing about fighters is that they are really good at the fighting things even without the short rest. They have armor, and hit points, and weapons ... They WANT the short rest, but they don't NEED it.
Next is the Warlock. Warlocks have one of the best (if not THE BEST) attack cantrip in the game. They have "always on" invocations. Yes, they need the short rests for spells, but it's perfectly possible to play a useable Warlock without the extra spells.
And that leaves the Monk. The Monk's abilities, and their various subclasses, are all premise on Ki- which is a unique monk resource. And ki ... is completely short-rest dependent. More than any class, monks are completely, totally, 100% dependent on getting the required short rests.
At least, that's my thought right now. Because I was thinking about this, and while some classes (Warlocks and Fighters) get hurt by a lack of short rests, Monks become nearly unplayable.
So maybe that's the crux of the issue. Maybe the short rest problem is actually a monk problem? Or, put another way, maybe the monk problem is ... actually a short rest problem?