Sanding a resin paste is only done when Time does not allow you to laminate directly over your pasted area or if your pasted area has such an irregular shape it is impossible to get a smooth consitant surface that you are happy with. With polyester resin the time frame is 24 hours to laminate before a chemical bond much be used (as long as air dry is not used). With epoxy the time frame is longer do to cure time but also dependant on the amine blush properties of the brand. The only reason I can possibly see to sanding between the standerd time frames is for a poor application where air viods will be present thus weakening the bond. Wet is definetly easier and more consistent (because air voids are elliminated as you roll because the wet paste conforms to the new cloth) as long as you realize that you cannot roll or brush or pack or whatever you are doing to elliminate the air to hard because this will move the paste and change the shape of what you are trying to achieve.

Dave.