If somebody else is doing them in the step 2 moving your finger along the shaft can take up to 1 minute.
I did this exercise for 5 weeks without any results only because I was moving too fast. My old stroke was like 10-15 seconds. Once I changed to 30 seconds I started seeing some progress

My problem with this exercise that I can't trap blood for more than 5 repetitions before my erection drops to 50%. (about 3.5 minutes)
As per description you need to keep your erection level between 80-100%.
I wonder if there any benefit continue doing 2 or 3 more repetition with the lower erection or it better to regain erection and start over again