yes alot of them fly in overweight most of the times the students don't even know. I checked my last trip; the a/c empty weight was 100lbs above empty weight in the manual due to GPS installed, different equipment,...
We were two adults, one of which a big guy, both had our packs for 4 days and the two long range tanks (39 gals instead of the standard 24)were topped up. Which would put us overweight of about 200lbs. No difference was felt in handling or runway length.
But normally we have some bigger cessnas with us on trips or a car, so they can take the baggage.