I've noticed this too! Either when missing a dose or having slightly fluctuating levels my libido is higher.
This post is long. Apologies. The thread title really struck a cord me as I've definitely had similar findings.
Here's my story and what I've discovered:
Over the years I've tried sooo many protocols and esters with my docs in attempts to dial in bloods, side effects, mood, libido, etc. I think I've finally found what works best for me right now.
I was originally prescribed the standard 200mg/weekly test cyp and anastrozole to have on hand. My bloods never dictated a need for AI however.
I've discovered I have a higher libido and elevated mood on a lower dose than 200 mg (somewhere between 100-150mg/wk), delivered w/ prop not cyp, no anti-e's, and no HCG. **This is just my experience over the years**
This was a game changer:
In the past year I tried Emeric's protocol - pinning low doses of test prop every day. It did make a slight difference (higher libido, far less E2 sides).
When I would miss a day however my libido shot up. So noticeably, that on "date nights" I would intentionally skip my morning dose from time to time.
Something interesting I learned once from an experience about 3 years ago - I pinned omnadren at my prescribed dose at the time (150 mg/week split on Sun and Thurs) I noticed a massive surge in libido. My GF and I were absolutely stunned in the difference once I started these omnadren I had. I thought for sure they were overdosed.
I did bloodwork a few weeks later on the same omnadren figuring my TT, FT, etc was simply higher and no... everything was in MY normal range. I thought that was bizarre. We're always shooting for the most stable bloods possible and as we all know, it's a challenge to maintain stability with the many esters in omnadren. Anyway, anecdotally it was a significant difference.
I now run test prop at 120 mg weekly and pin MWF. I've found this is my sweet spot and libido is the best I've had in recent memory (without being on cycle obviously).
I think there may be some merit to not having 100% stable bloods 24/7 when running longterm trt. At least when it comes to libido. The body doesn't naturally operate the exact same way that exogenous test behaves. There's nuances in nature.
The human mind and body is so much more complex and nuanced especially from patient to patient.
I'd say experiment under the supervision of a knowledgeable doctor and bring those questions up. Thats fantastic you've made that discovery for yourself.