the PA28 i fly is supposed to be landed at 75 kts at MTOW but on my last flight i was solo with 1/4 fuel and i had no prob landing at 65.
These figures seem quite high. A PA28 will land at around 50-55Kts with full flap. Excess speed can cause a student to think they have done something wrong as the float seems to go on forever while it bleeds off, making you think "will I run out of runway ?" This tends to make you try to "force" it onto the ground before it is ready, usually resulting in a poor landing.