The book I was using for my last post was written before the invention of acrylic paints. The author was most often using oil paints, which would probably account for his doing all of one color before starting the next. Oils can take a long time to dry, while acrylics tend to dry quickly.

The project I'm working on right now is somewhat similar to stenciling, only I'm blocking off the areas that I don't want to paint using blue tape instead of a stencil. I'm layering several colors. My own temperament being what it is, I'm finding that I need to complete all of one color before moving on to the next in order to keep things relatively consistant. But I have a peculiar temperament, so you might find things work differently for you than they do for me.