Thank you Claudemir and Carl,
Hmm, even if he didn't get a good likeness, I think some people must just paint very fast. I'm not worried about painting fast, first I must learn how to paint well, but it just really struck me that someone could paint a face to such a finished level in one short sitting.
Even if his paintings were rejected sometimes, I think so many of them are beautiful today, and at this point the likeness doesn't even matter since it's some 200 plus years later.

So, even for a figurative painter he was fast. I guess it takes a lot of practice.
Joan