FWIW, when I was painting my car (done now, pics soon.) I never rolled the coats right after the other. I would do one coat at night and roll the next coat probably 12 hours later. I stopped rolling thurs and the paint is already hard and not easily scratchable. This is done in ~40F weather indoors no heat.

I rolled the first two coats with the aluminum, then sanded with 800, and rolled the final 3 coats with light machine gray. After that I stopped cause it looked so damn good! I have yet to sand with 1500 and polish, gonna wait on that since I need to give up the garage I'm using. It still looks damn good and shiny. When I run my hand over the paint it feels sooo smooth except for the tiny pieces of dust spread randomly, maybe like 3 pieces per 10 in by 10 in area.
At least twice today when I was working on the car my jack banged into the door and I jumped cause the paint but when I looked: NOTHING!