You can always spot some on. I hear of guys using spreaders and stuff like that but as efficient as that sounds it also sounds like some is wasted when mixing. Why are you epoxy priming and letting it cure? Are you protecting metal for storage?
I ask cause most people use epoxy as the barrier between paints/surfacers and your metal. It's the most dense of all primers with the best adhesion so it's ideal for DTM applications but in my opinion it's best used wet on wet with a surfacer, meaning you let it kick for about 45 minutes after spraying then apply your surface primer OR paint when used as a sealer.