Yes, that sounds and looks good. When I was doing some, I had different colours for forehead/nose/lips/cheeks/neck/eyelids. But is still had the problem that in real life the colours are different everywhere. The luminosity changes are fundamental, but the actual colour and saturation should be changing too. Your technique adds some instinctive artistic input to make it more natural.
An idea for an experiment. Take a colour portrait. Make it monochrome. Colourise it without looking at the original. Now do a really detailed comparison and see what you can learn.