At the end of the day it takes what it takes with numerous variables. I recall in the days of flying scholarships continuing with one student after her 20 days/and 20 hours and completing the PPL in another 15 days, so 5 weeks in total. She then did not fly for another year by which time much had been forgotten. I have always regarded 6 weeks as a practical minimum. If you have 2 or 3 students it keeps you busy.