Epoxy generally doesn't need sanded if recoated in a short window.Some are also sticky or rubbery and clog paper easily,an exception is SPI brand epoxy,it sands easily after 12 hours.If you are doing bodywork/filler over the epoxy,I'd sand it lightly (so you don't sand through)with 220 grit paper and use a red scotch brite scuff pad on the edges.
RT