That sounds pretty odd... Is he using fibreglass or literally just brushing resin on it? He's using epoxy right?

Can you feel the cracks or are they just showing through what he's done? Shouldn't be anything special needed for the repair.

I'd sand back the damaged areas until the damaged parts are gone and then wrap a new piece of 4oz cloth about 2" bigger than the damaged area, laminate it with epoxy and tidy it up with sandpaper once it's properly hardened. Then finish coat it with more epoxy (with a little additive F added if you have access to it) and then sand up to 400 or higher to finish it in with the rest of the board.