While this is true, at some point it becomes a mockery when you can look at the record of training and see a steady progression though the 61.65 requirements, only to be finished up by a -II. It looks to be a deliberate end-run around the intent of the regulations.
My issue with this, and why I agree with midlife, is that you say issues are covered by a CFI then finished by a II. When in reality it could be joe the currently being trained instrument pilot providing training as a safety pilot. At least in the case of a CFI it is an instructor.
That said, 61.65 needs to be covered in it's entirety to be able to sign off the student as a II. So the 15 hours has to cover all of it. The other 25 hours can be done with anyone and if you want to do it while logging instruction (not towards a rating) then more power to you.
Consider this, 25 hours with a safety pilot. Or 25 hours with a CFI doing all of the 61.65 stuff. Completion with 15 hours with a II doing all of 61.65 for the final sign off. The guy who went with the CFI got more than double the training and they both met the regulation.
Edit: I don't agree with a CFI charging to give instrument training at an "instrument rate" if there is a difference. The charge should be whatever you charge a typical private pilot. I know some places charge 10-15 more for instrument training.