I have driven hundreds of thousands of miles as well as untold hours on tractors and the only clutch I ever took out was on the pulling tractor.
You kind of expect that to happen eventually though.
The delivery van I drove was a P-30 Chevy Stepvan. 350 engine, SM465 transmission.
I had to pull the transmission to replace a throwout bearing after it had about 50-60,000 miles on a new clutch.
The clutch disc was showing 20% wear, meaning it would last another 200,000 miles. A lot depends on the driver, and whatever (bad) habits he has with a manual transmission.
Our IH farm tractors' clutch life depended who the primary driver was.
Normal expected clutch life (per IH) was 2000-2500 hours.
The tractor I drove a lot went 3600 before it needed replacing.
The tractor Dad drove went 1700 hours. (He liked to slip his a lot.)
Both were 90+ HP (Farmall 826 and 806, respectively)
Speaking of pulling tractors, my brother and I had a hopped up 1066, that had it's clutch (Crowder 2 disc) take a dump on us right before a tractor pull.
We had the tractor torn apart, clutch replaced, and back together in 45 minutes!