One thing I’ve done..
Is to measure the length as I go. I read somewhere that bodybuilders will sometimes do this and then stop at the max pump. I’ve tried this off and on for PE.
For length, I’d use a dry jelq/squeeze technique. My penis bends downward so I’d grip it with my left hand around mid shaft and squeeze blood toward the head. Then I’d move into a Jelq grip but at the same time, bend the head upward and Jelq it forward. In doing this, I’ve been able to measure length gains during the work out. Next, I’d set a goal of say 1/8 or 3/16 or sometimes even 1/4” and work toward that. Obviously the 1/4” work out is timely and if you’re recovering from an injury, not recommended. However, you get the point. During the routine I’d jerk off a little to stay ridged and near climax.
My best length experience was when I was doing the above exercises along with staying on the edge of climax but practicing the kegel to hold back the climax. I’d keep a ruler close by and measure every few minutes just to make sure it was working. I think the key to this particular session was keeping on the edge of climax but not having the orgasm and obviously combined with the stretch/squeeze/jelq.