What amazed me when I used to fly them was that nobody actually knew the real range.
They were of course flown full-rich so the range was about 20-30% less that it should be, but even then nobody knew. They worked on the tech log being OK for "3 hours" or whatever, but nobody actually checked how much was left in the tank when they filled up, against expectations.
If I was flying seriously in a C152 or similar I would measure the fuel flow accurately, using test flights.