The sweet spot for my shower can be found by tapping the handle up or down with less force than a mouse click, like I think this moves it a micrometre.
Exactly how I do it. I start it running for a few second in the general middle spot, and tap it either way. It’s going to vary where that is summer or winter, but fortunately the handle isn’t too tight and I can get it with a few taps.
I had one shower in an apartment where the temp was set by twisting the round knob, but turned on by pulling out the whole thing. Perfection.
I have no idea why thermostatic mixer valves never caught on in most of the world.
Are thermostatic shower mixers not a thing where you guys live?
This is a thermostatic shower mixer. This is what happens when they seize up with limescale. This is not normal operation. The cartridge needs to be replaced.