3hrs wow can usually have them off in about 15min hate to see the labor bill for that $10 seal.
Stihl list price is 45 minutes each way + 15 minutes for cleaning
I use that for labour costing as it is the only complete pricing schedule I have.
And this assumes that the mower is in a new condition, clean with fasteners that come out easy which is rarely the case.
The total labour for a lower oil seal is 2 hours which is what I charge out.
Even then there are times it can take near an hour just to get the pulley stack off.
Usually I can do a seal, mower in / mower out in around the scheduled 2 hours if I leave the engine in place.
Removing it can easily double that time.
A side banger with side exhaust that does not need to be removed could go out & in, in those times.
Even better if you don't have to remove the hood & side panels.
Very few OHV ones can be done in those times.
It can take better than 15 minutes just to get the muffler off on an old engine.
Then there are old rusted mounting bolts and corroded mounting tabs on the engine which are prone to breaking off if you are too violent with them.
Kawasaki allow 2 hours each way on warranty work for replacing the engine, which is about the only charge out in their schedule that is reasonable.