Time between coats is called "Flash Time" it is when the material goes from shiny to satin as the solvents evaporate. 10-15 has just always been a guide line. If you lay it on thin it's going to "flash" faster then laying it on thick. Better to be somewhere in between. To light of a coat (dry) will be grainy, hard to sand and poor adheision . To heavy and you'll be sanding runs, trapping solvents and wasting material. NOW! If your compressor isn't big enough to keep pumping enough air......Turn your air pressure down and your fluid flow down. The less material goig through the tip= les air pressure to atomize. I have used Slick Sand, G2, Feather Fill (all Polyesters) with a 1.4. reduced 15-20%, 20PSI, fluid turned in and moving very slow. It wasn't what I wanted to do....it was what I had to do as a work-a-round in a pinch. Soooo, Watch your flash times and DON'T LEAVE ANY IN YOUR GUN BETWEEN COATS. Look, yes I leave it in my gun for the first two coats. Then, I dump my gun, give it a good rinse before I load the 3rd coat (if you have had polyester in your gun for over 20-30 mins it can start to "go off" at that point it take about 5 mins to turn into a brick of primer in the cup.....well, that's all I have to say about that...da Bat