Neck Bridge question

This is a dumb question, but when you do these, is it for reps or do you stay in the position as long as you
can? I've always just held the position.

I've done both ways. Doing reps gives me fewer pinched nerves in my neck, for whats it's worth ;p

As an aside, Obake (Tim Catalfo, mma fighter and chiropracter) is firmly anti bridges. "Bridge when you have to" is what he told me. Take it how you will.