Digital painting methods?

When I watch speed painting videos I notice that artists use three different methods for painting. Are these methods prefrence or are they used in different situations?

Method 1: sketch->line cleanup->flats->shading->details->compositing

Method 2: sketch->line cleanup->greyscale->shading->details->coloring->compositing

Method 3: sketch->color shading->details->compositing

I’m not what I would call an expert on the matter, but I am an artist and would have to say that there is probably a method to the madness. This being said, it would boil down to your preferred method. I would try them all out and find out what best suits you in those situations.