If it's within the manufacturer's recommended time period for no sanding since you applied the previous coat (3 days for System 3, don't know for other brands), then just roll on the next one. Each new coat will fill the weave and round the sharp pointy bits some. Only sand the final coat.

Laszlo

Once fiberglass is properly wetted out, additional coats of epoxy to fill the weave are not needed for strength. On the outside of the hull, the smooth surface created by filling the weave is obviously desirable. On the inside of the hull many builders leave it rough to save weight, time, and money. A rough surface underfoot is also good for safety.

Grant

Even if you don't have to, I find that a light hand-sand with 120 grit paper between coats does not hurt - and I like to avoid any sharp bits wherever possible.

It is not a requirement if you are applying the next coat within a day of the last one, but, I say get rid of any sharp bits ASAP.

It only takes 1-2 rubs over with a new sheet of paper to get rid of the worst bits.