From my experience, spray on paint can stay wet for quite a while too. I have used both spray on and roll on paint and find that either one usually takes about an hour before it's dry to the touch.

So in other words, I'm not aware of spray-on paint drying any faster than roll on paint, especially when the roll on paint is thinned way down with mineral spirits. In fact, the roll on stuff might actually dry faster in some cases.