I felt like (and number indicate) I was able to perform higher volumes in my training. While I may have fatigue at a certain level or after a certain number of reps, I feel like I didn’t have that as much. One interesting example I can give is that I started up with depletion push-ups after not having done them in months. I have done them in and out of my training for years (since high school), so I have a good idea of what I am capable of with my 1rm:bodyweight and how fast it will come up. I normally start out anywhere from 40-50 or so (chest touching ground and back up) when I first start and then go up to 70s, 80s, etc. I have never done more than 50 the first time out and this past time I did 65 (though my PR is 92 after a bench workout). Mind you I was not doing any high rep work on bench or any other presses and my 1rm, if anything, is down from where it was last time I was doing these.
So I guess strength endurance, general fitness levels, etc. It is cheap enough that the minor, but significant improvements in performance are worth it to me.