How trustable are the top lap times for each circuit, and if they arent where to look for real benchmarks?

Hello everybody. I am very curious on how trustable are the results on top of each leaderboard. I have a particular way to enjoy this game i select a track and only do time trial on it for approx 4 months until i get really good at it, but i would like to know what other people can do but sometimes the gap has just ben unfathomable.

Ive been driving monaco for 4 months getting a best lap time of 1:12.7, but the leaderboard says the bast lap is 1:07.5(???), like ill admit there could be 2 secs in my lap (on a perfect day), but 5.5??? no way.

The same goes for zandvoort, im doing a 1:10:3, the gap between me and the top guy is 2.8 secs which i cannot find believable. It is entirely possible that im just way worse than i thought, but i do have my suspicions. SO i guess the question is are they real and if not where do i look for realistic benchmarks for top times?

Thank you for any answers, Godspeed