For me, sensory overload happens fast and can't be waited out. It can be caused either by a lot of stimulation (light, noise, people) or by a small number of scary objects that I fixate on, in case they're about to try something, even though I know I'm afraid of some stupid things that can't possibly hurt me. Then I get tunnel vision and I freeze up and any further stimulation (including, unfortunately, people trying to help me) becomes completely aversive and I need to hide or escape until I can deal with the world again.
I've gotten way better at "shielding", though, and this doesn't happen as often as it used to.