Adjusting the belt length doesn't hold.

[Mr__]

I noticed when you adjust the belt with the slider to shorten it to provide more tension it doesn't stay in place long and quickly moves it's way back up to the top near the clip... anyway to keep it from slipping?

 

[ronjohnson69]

Adjusting intensity has more to do with where you anchor it to your body.
Putting it around the lower leg usually allows you to stretch extremely intensely but it will severely limit your mobility.

I don't think there's a good way to wear an all-day stretcher very intensely without being mostly stationary.
Another problem is that the intensity always changes based on your posture/position of the limb it's attached to.

But keep in mind you don't actually need that much tension for gains.

What I personally did (which is unrelated to your question) Was that I made an anchor point on the wall beneath my desk, where I attach it for max intensity without any fluctuations in power no matter where my legs are placed. I just used some cheap velcro.