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.
