All of them hundreds of times?Are there actually any 5e modules that do this?
Well... so far I finished DMing Lost Mine of Phandelver and have an ongoing Princes of the Apocalypse campaign and I think pretty much every 5th encounter has a sentence about some creature escaping when a condition is met (usually "losing the battle" or "left alone").
But I handle it like how most others here do, just stick to the rules and let the creature die.
I was just wondering because often players miss out on even seeing half the creatures abilities, because they have this habit of keeping everything grappled and even if the creature has say the ability to move through walls, that doesn't help it when its speed is 0. Of course I could change the ability to "It can move through walls and is immune to the grappled condition" in preparation, but still feels like cheating to me. Then the module should have thought of it.