When you enroll on a PPL Course you are normally given a book containing all the flight Exercises
or
You will need one of these to read up on the next lesson. The speed at which you progress will not be the same for all students so don't assume that all students will cover exactly the same amount in a lesson. The books list Exercises that do not necessarily equate to an equal number of flights.
It is very rare that an Instructor takes a student just for money. Most instructors would prefer a student who progresses quickly rather than one who takes for ever!