did a 3901 with 12 hours on it.
operator was pushing dirt with it, using it as a bulldozer, and in doing so riding the clutch pedal. You cannot use the clutch pedal to vary the speed of the tractor under that kind of load, you have to take your foot completely off of the clutch pedal and let the lowest gear do the work.
If you had an HST tractor you wouldn't have to worry about the clutch but people get set on "I lose 5 hp with HST" mentality. So what, what you lose in HP you gain in longevity of the clutch. The extra $$ you spend for HST you make up for when you have to put a clutch in. Especially the two-stage clutch.