I did Kegels for I'd say a month non-stop. If i was walking somewhere, sitting in class, I was doing Kegels. This aloud me to kegel up to an erection but as soon as I let go it would go back down.
I've been focusing on reverse kegels now . . .I think this has helped me last longer in bed. If you're going to build up one you should always build up the other IMO. So do reverse and regular.