Chances are it will vary.

I've bin doing them for a while about 4 weeks and i've noticed a difference, main thing is when I masturbate it doesn't take a few strokes to cum, its quite liberating hitting three minutes, then five minutes then 9mins etc.

I beilive they work, and if your bored in college, uni or work its something easy to do to pass the boredom :)

Be careful with these exercises. If you feel any pain stop immediately. I would recommend not doing them at all. I did these and jelqing exercises which are for penis enlargement. I ended up injuring myself and getting chronic epididymitis and prostatitis from doing them. I have had both these for over a year now and i'm telling you it is not worth the pain that I am being put through. Trust me man, I wouldnt do them if I were you.