It's always great to see how others work. Your end results seem to suggest to those not in the know that it comes easy. This progression shows that there's a ton more work involved than many may think. : )
For most, the difference between steps 4 & 5 may not seem like anything... but in reality it's a lot. Stopping @ 4=great; going to 5=exceptional!
Usually 2 layers. One for the lineart, One for the color underneath, then I eventually merge them together and do more details.
It feels more "real" if you get what I mean. Like a traditional painting, if you make a mistake, just paint over it Plus it works better to blend the colors and build textures (and my poor, laggy computer thanks me for it too!)