I've been reading about how a lot of folks do daily pumping, sw, etc. and are having little of no results.
Years ago I tried the foreskin (restoringforeskin.org) restoration route to see if it would increase my sensitivity.  It didn't do much for my sensitivity but it increased my circumference from 4.1" to 6.25".  Not much on the length but I've had a really thick dick since then.  While I was working on this I found that it had a definite negative impact on my erections.  The more I messed with it, the softer I was.
Move forward 20 years...
I had gotten into porn and masturbation, more than was healthy.  My erections suffered and I tried shockwave and pumping.  The pills weren't working and I was getting pretty bummed not being able to satisfy my girlfriend.   I noticed some early improvement with sw but I really think it was the placebo effect.  
We spent a month near a remote island in the Bahamas on our boat with no internet, no cell coverage, and no masturbation.  Voila!  Things started working again, #4 erections with no pills.  Daily sex, Good sex.
When we got home things went back to normal  SW, Pumping, porn, and masturbation.  No good erections, no sex.
This got my attention as I've been a test engineer for many years.  I stopped sw, pumping, porn, and masturbation and after about 2 weeks things started working again.  We now have daily sex, often multiple times.  I think this is attributed directly to not messing with my dick unless  sex is involved.
I think this might be why the healing part of sw seems to  help.
This probably won't work for everyone, but it surely is working for me and we're both happier than we've been in a long time.
Good luck, and hands off