if in a group, do what they do to maintain speed unless you're about to get dropped or find your braking is different from them. Than pedal to get back on. If near side by side or few bike lengths between, coast with them. Save your energy for the next hill work when they get to tempo. If you are following each other, at the bottom of the hill, you will carry momentum better then them, either pass if safe or feather brakes to maintain speed.

Don't feel guilty about coasting, ride smart. Learn to play your strong suits and use the saved energy down the road