Being startled in the woodshop is never a good thing. It depends, of course, on what you’re doing.
The worst result of a sudden scare while idly reorganizing your hardware bins is usually having to pick a bunch of screws up off the floor; the same scare while routing could result in … well, I’d rather not think about it.
Because you’re often so focused on what you’re doing it’s easy to be startled while working, and despite past experience you can never really prepare yourself. Yesterday I was listening to some nice music and doing some light hand-sanding without a care in the world when my compressor kicked on. Jumped out of my skin.
There are countless ways to be scared while working: That compressor, the phone, a sudden banging on the garage door (I put a little magnet sign on my front door noting I can’t hear the doorbell when I’m in my garage shop), a car horn on the street, a misbalanced object falling from a shelf or worktable, a spouse who shall remain unnamed walking up silently behind you and saying, “Hi, I’m home!”, a band saw blade breaking, minor kickback, leaning on my dust collector remote switch, pets sneaking into the shop, or even a light bulb suddenly burning out.
I’ve been startled by all of these things, some of them far more than once. (That spouse shall still remain unnamed.)
Bet you can think of some more.