I have not done much napping in recent years, but I recall in summers during college when I waitressed that I'd go home tired from work, take a 15-20 minute nap on the couch, then be ready to do something else for the evening.

I also took naps for survival when I had one infant at home with me. With all the nighttime feedings and my baby being such a slow, fussy eater, it would get to be 6:30 or 7 and there's no way I could get up for the day. I'd put myself back in bed and nap till the next feeding.