If you are experiencing negligible gains, there are a couple of things you could try. One is to assuage your current intensity levels that you perform at, and maybe you should increase your intensity for the following sessions and note if you are benefiting from an increased intensity level.
Or, you are becoming very acclimatized to your techniques in your routine, and it is time for new stimuli, namely, new techniques altogether!
You could possibly become bored with doing the same techniques over and over, and this could lead to a drop in your focus and concentration, further leading to a ho-hum workout session. Now you are depriving yourself of a quality workout, one that should be progressive, but is now going nowhere!
PE takes time, though, and you have to give yourself a respectable time frame in order to pass judgment on whether certain techniques are working for you!
Just be aware of how your penis is feeling and responding to the exercises!