Hey I'm glad you find them useful And yes, painting background to foreground is really helpful if you're worried about making mistakes or if you really like building up subtle layers (which I love love love ^ ^)
you should work all of your paintings this way, not just watercolors. for one, it's easier to avoid mistakes (such as getting too dark too soon) which could be irreversible. when you use watercolor your brightest highlights should be from the white of the paper. in this particular painting, the figure is lighter than the background (lighter things come foward, darker, duller things recede) so working the background first was a way for me to preserve the white of the paper in the areas that i wanted to be light.