I discovered in the late 1980s, that it took me 3-5 hours per figure to do a really nice job. I painted about 5 ACW figures that way. Since then I’ve painted about 20,000 figs to a much, much lower standard. If I painted them all to a high standard, I would get about one fig per week done, so I’d have to live over 380 years to paint what I’ve painted in the last 30 years. Then I’d still have all of the sculpting, casting, scratch-building, and terrain building to do.
I paint to a pretty low standard, particularly on 15mm and smaller, and do only slightly better on 20-28mm figs.