Unhooking and Healing

I generally wait for the TR to fade out and then some. Give the killer at least ten seconds to walk away from the hook. Generally, more is better and I prefer to wait a bit on my gen or whatever before going for the unhook, unless I have confirmation the killer is in another chase or I know they're leaving to pressure a gen with Tinkerer.

Healing under the hook is a risky move unless you know the killer is busy with someone else, or they teleported away and cannot immediately teleport back. If you have We'll Make It, sure, heal under that hook, but otherwise it's better to move a moderate distance away behind some cover. (However, if a survivor wants to take you across the map to some obscure corner, they're wasting too much time and don't bother with them. It's also possible that they don't want you to heal them if they aren't stopping in any reasonable time - Resilience, Pharmacy, Inner Healing, etc.)

That said, if the survivor's still waiting under that hook, I'd heal them anyway unless you know the killer is coming back. Since communication is so difficult, it's often better not to fight a stubborn player unless you have confirmation that what they want is a bad idea.