Just to be clear, I don't believe the results are that good from what I have see. I have been restoring and colouring photos for 11 years and find any short cuts to colouring don't do justice to the photos, but, that's just my opinion. I always enjoy colouring a good photo and prefer to choose the colours that I think would suit the subject matter and the era.
I am only aware of one restorer on here at the moment who chooses the method that you mention. The way it works is, we all restore and colour our own work. If anyone wants to colour a restored version done by some else, they need to ask their permission to use it to colour first.
Have fun.
Carol