First I want to thank Marc for making the great tutorial which taught me how to do speed paints.
You can find it here!
Now I want to share my first one I did a bit over two years ago, total time was 3.5 hours.
And my most recent one. The first one I did a straight up painting, which was a real challenge for me and the thing stayed in a 'looks very bad' phase or a long time. I've since done a few in the same manner. For this recent one I used a work flow similar to comic color. So I had my lineart, then I made flats, then I rendered. I rendered using a screen layer for the light and a multiply layer for the shadows. Various overlay layers, then finally a screen light layer for the final high lights and rim lights. You can see them in my process photos. Total time was about 5.5 hours. I hope to share more!