I also wondered how a 5 day intensive course would work with the 100 hour rule. Even if you did 24 hours per day over those 5 days, that would only total 120 hours and you are never going to do 5 complete 24 hour days.
On the subject of why it takes 50-65 hours to complete a PPL, you also have to take weather in to consideration. My PPL took 58 hours (I am in the 45-50 year old category). I added a few hours because when I turned up I couldn't do what I was supposed to do due to weather. Rather than not fly at all, I usually did circuits or something local to keep in trim. I could have easily knocked 5-10 hours off that figure if I had of had perfect weather for every lesson booked.