I am too lazy to type in the quote, but Dr. Alan P. Brauer writes in Eso Extended Sexual Orgasm that some male clients in his sex therapy programs have gained as much as an inch in size while following his program.
ESO: How You and Your Lover Can Give Each Other Hours of Extended Sexual Orgasm
http://www.amaz … /dp/0446677620/
He attributes this to the frequency and duration of erections required by the program -
To simplify a whole lot —- essentially the man "trains" himself to retain a very strong erection of 30 minutes or more. With partner sex, each partner’s aim is to keep the other on the edge of orgasm for a minimum of thirty minutes.
It is a real good book - basically "tantric sex" without getting heavy into the philosophy. Lots of exercises for your self, her, and together.
So my theory is that these longer duration erections may be very good for cementing gains. Whether they be from edging or sex with a partner.
Just my theory I am sure many will say I am a crackpot. But what the heck, it is fun.