We have our older tractor for about 7000 hrs.
PTO clutch plate is still original, and drive plate was replaced due to broken clutch pins, at about 5000 hrs. It is worned about 2 mm, so it will last a double # of hours at our way of tractor usage.
No FEL, just ordinary ag work as mowing, plowing, disking, planting ... and lot of road transport use.
Dry clutch life is highly influented by the operator's habbits, and proper maintenance (check free play of pedal).