I think one of the great things about individual tuition is that you don't have to take the same track with all students. So it's difficult to say what I do, because it's different for different people, but I do have a general approach.
I use method books - usually Piano Adventures, either Accelerated Piano Adventures, if the student is established on another instrument, or the Piano Adventures Primer if they are young/a complete beginner. At the end of the Primer I take a view. If the student is progressing slowly, I will move on to Piano Adventures Book 1, but if they are picking things up really quickly, I'll move to something like Piano Time Pieces, so off method and onto repertoire. Alongside this I would use something like Adventures with the Keyboard Monster, to focus a little more on technique and expressiveness without worrying about notes so much.
At the end of PA book 1 I take stock again, and either continue with the method if they are still inching along, or onto one of the repertoire books - eg Upgrade 0-1 if they are progressing well.
Once "off method", I tend to secretly introduce some grade 1 pieces along the way, to gauge whether the student is up to tackling grade 1 yet. I don't usually do the Prep Test as I have found it is a bit of a blind alley.
Hope that helps.