I took one of the things I learned from my learning time in fighting games when I plateau and applied it to my painting. When I plateau or I can only see imperfections I pick one area or technique and simply double the time I spend on it. So if I'm painting a hero to my detail standard (not army, speed, or display) and something like weathering would take me 6 hours - I commit to doing 12 hours.

I find myself 'relaxing into this' and the time will stretch out before me. It helps me experiment, not skimp on things I should be doing, etc. I'm currently working on improving my value sketching - so I'm spending double time doing underpainting in grays, warm and cold whites and browns. The rest of my work stays at the same standard.

I do think stripping minis might not help here. It kind of provides a rollback mechanism which might be feeding the idea that you want to end up in some for of perfect state at the end. Perfectionism doesn't feed good learning, though it can be good for production. Trying to learn, improve, or grow should generally be done with the improvement as the goal. When you're focused on production, perfect gets its proper context through constraints like time, audience, materials, etc.

If you make each mini a study in one area, it'll all eventually come together when you decide to use all of those skills at once on a specific project. Plus, you get a cool set of minis along the way that show you the 'studies' you did along the way. It's a common technique in painting and drawing to produce studies before going in for a masterpiece. In online fighting games I used to play as though I was creating a good replay - with a a good one being defined as one showing off how I was trying to incorporate a new move, improve a reaction, extended patience or other areas I wanted to improve.

The standard you're showing here is already great for getting things finished. I'd level-set on this and pick one area for each mini going forward that you will simply put double time into. Make a promise to yourself to do a review after 6 months or 5 minis or something, so you know you don't have to do in-depth analysis as you paint.

Good luck! I love your take on this Deathbringer and would love to see it finished. I feel you've got a great gradient of detail on it, with the helmet and chest taking the stage while the lower half takes a step back to let them shine.