OK theory of flight covered!
How are you paying ? Tacho hour or hour meter?
If it's tacho; it most probably divides the revs by some number like 2400 and registers it as minutes
OK guys ... yes they're in tenths of an hour.
What I'm getting at is; fly for an say, an hour, at 2100 RPM; the tacho says 52minutes while the hour meter comes up with 60 minutes. From start to stop the difference is even greater... low RPM on approach and taxiiing while the clock ticks on relentlessly..
At 200 bucks plus, per hour, you pay over thirty bucks less for the same flight and bung the sixty five or seventy minutes total flight time in the log book.
Cheating ??? NO! The tacho time is what the maintenance is done on and the flying schools get paid by the hirers, for the time the clock runs... probably get paid for 110 hours in the 100 hourly period.
You can open the window in a Cessna and get good clear photos or see clearly in medium turns and aviod the need for forty five degree turns.