Following the manufacturers guidelines gets me a perfect bleed every time, as long as I follow to the letter. SRAM or shimano. Using the epic bleed kit for both.
I generally cba though with shimano, I just bang in new fluid from the caliper with the yellow block in till the fluid comes out nice and pink at the top. Job done in a couple of minutes, usually needs the levers taped to the bar overnight if you don’t put in fresh pads though. Gets a bleed that’s almost perfect.
Anything avid or sram you can’t cheat with.. Follow the guide to the letter or you end up with no brakes. New guides way better.