Depends on the hill - and also whether my legs are super tired.

My top gear is a 50x11, so I spin out at about 38 mph.

If I'm not spun out, concentrating on sharp turns (my cornering skills aren't the greatest, plus there's a lot of gravel in the turns here) or completely worn out, I'm likely to be pedaling at least some. It keeps my legs from stiffening up, so it won't be a complete shock to them when I have to start pedaling up the next hill.

I've never ridden with a group so large that it really matters as far as group etiquette - we might get in each others' way a bit on the first couple of hills, but after five miles we get strung out enough that it's not an issue.