short rests work like they do in almost any game ive ever played: short rest is when youre not in combat.
And thats probably what they were designed to do anyway
On rules, you need to spend a hour to count as a short rest.
You who always complains about arcane casters being OP should know that warlocks gaining his spells on a short rest means that they would be extremely broken if all of his spells are per encounter. Imagine warlocks having Hold Monster per encounter while wizards needs a long rest to re cast Hold Monster... Great old Ones warlocks able to cast Evard's Black Tentacles every battle.
Wizards (And land druids) also regain some spells with a short rest in 5e, too =)
ED: Without short rests, ritual casting and outside-combat spells to RP, wizards will possibly lose some of their usual flair.
I read some posts asking for cooldowns between combat to replenish over time abilities that are recharged in short rests, like fighters´ second wind , wizard and land druid spells, warlocks incantations, etc But let´s imagine what is going to happen if Larian decides to use something that remotely seems akin to a cooldown. The backslash could be brutal.