I don't think running hcg on cycle makes a massive difference if you're talking about an old school cycle-pct. It may help, but hcg is mostly only well studied for TRT levels and durations, not cycle levels/durations. It's apparent that it will help maintain testicular function and spermatogenesis in that context, allowing you to more easily recover natural spermatogenesis or even improve beyond your natural semen parameters with drugs. But using it vs clomiphene/enclomiphene as a monotherapy just to restart endogenous testosterone production (with no concern about fertility) is not well studied from what I've seen. I agree that sensitization is not a big concern, I've read a lot of studies on hcg and never seen this mentioned, although it's possible.
As far as taking it before or after ending a cycle - Hcg does shut down LH production but that suppression is typically short-lived. There are plethora of studies in using hcg treatments in men for improving spermatogenesis with no long term detriment to natural lh production noted.
Hcg is much better at initial restoration of testicular volume, which is often correlated to intratesticular testosterone production and hcg montotherapy will increase your natural testosterone production, IE hcg will get your junk working better faster. This is also backed up by decades of hcg studies in men.
Although it was not previously understood well, we know now that intra testicular testosterone is a major factor in male fertility (this is also probably why massive test cycles will show increase in testicular volume and swimmers in some men). Even if fertility isn't a primary goal, healthy intratesticular testosterone seems closely correlated to general testicular function.
Anecdotally, I was able to reach high in-range testosterone levels with hcg montotherapy last year. Switching to clomid later, I was not impacted at all in restarting natural LH and FSH production. I simply tapered off hcg and did hormone panels before, during, and after.
Response to hcg, fsh, and SERMs also seems to be subject dependent as well as preparation dependent. Despite multiple studies showing massive benefits of FSH to spermatogenesis, for example, there are FSH non-responders. One recent study looked at changing preparations and concluded that FSH non-responders can benefit from simply changing preparations/brands.
I think all of this is further complicated by our ability to source these items. Are you actually getting enclomiphene or is it just clomid? Whose hcg preparation are you using? Hcg seems to be all over the board in testing and "low" testing Chinese hcg has worked better for me than Indian pharma that tested better. Is that an individual response, luck of the draw in batches, or better bioavailability in one or another? I couldn't tell you.
