I do kegels twice per wk, starting off 3min of light, partial contractions, then 10min contracting hard and holding for 5-10sec. I finish with 5min hard contractions without holding. Sometimes I hold one contraction hard for 3min. I don’t see the use of holding any longer than that!
Also I Kegel for 5min (first 2min are soft and slow) before warming up for a jelqing session. I EDGE 2-3times Per Week.
Doing this, it was only a few months before I could have multiple orgasms.
Try not to cheat by using your abs too as you contract your PC Muscle.
I am not expert - and we are all different and live differently - but I do not believe holding a contraction for really long will serve any purpose. The point is strengthening the muscle by contracting as hard as you can over so many reps so when you EDGE it is easy to to hold the contraction and orgasm without cumming and maintaining EQ and hormones.