In answer to your question some time ago,
zetreque, Prince took about 6 weeks, but it did sit unattended for long periods, or maybe I would intend to work on it, but just sit, thinking about it. Very frustrating.
Other times a work comes together more quickly. This one, I started yesterday afternoon and finished, more or less today. May still tweak it, but maybe not.
It is the gas station of my childhood just up the road. Painted from a photo, and best memory I could come up with. It is now a restaurant, garden center. Also working on the local railway station from the same period.
My work is at
https://twitter.com/DWiliamson