Everything works once

I've been at this for several years now and am quite frustrated. However, I've felt plenty of new and exciting sensations over that time, so I'm highly motivated to continue. Where things go wrong is when I try something new. Whether it's a new device, technique, lube, etc, it generally only makes a difference the first time I try it.

Let me give a few examples:

The first time I tried the tempo, I was getting the best response ever. I was convinced I had found my prostate's preferred toy. Well, after the first time, it no longer stands out over any of the other dozen or so toys I've tried.

Another one is the first time I tried the mindgasm lesson for the top muscle. I felt a very strong, sharp pleasure that seemed to go in a line from about just above the base of my penis to my belly button. I was so excited. It felt amazing. I had the same sharp line of pleasure the next time I orgasmed during sex. It seemed obvious to me that I was on the cusp of a breakthrough, but it's never happened again since those first two times.

The other one that comes to mind is the first time my wife massaged my perineum during oral. I felt a very sharp pleasure spike right in my prostate, probably the most intense I've ever felt. But, you guessed it, it never worked again.

I seem to have the same thing happen in other areas of life. Whether it's a new supplement, a new mental or spiritual practice, or a new exercise or stretch, I seem to respond to it really well at first, and then fairly quickly whatever it is stops working. 

This leads me to suspect there is some sort of mental block or hangup that is holding me back. Maybe even some sort of subconscious fear of success. I've tried some self help ideas to overcome and sometimes it feels like it's helping, but of course, then it doesn't. 

I'd love to hear any suggestions or advice regarding this issue.

(The only thing that has worked for me consistently is cannabis. I've only ever used it for prostate play and it's always been very effective for me)