I can't speak to zero turns, but I have a 22 year old JD lawn tractor with a Kawasaki that does 2.5 acres sometimes twice a week without a hiccup and plows the 100 yard long driveway all winter. Good engines.
My 1998, 445 with a 22HP Kawasaki rolled over 1800 hours this winter. Not sure what model you have, but mine ate the plastic oil pump gear at around 1600 hours. Luckily, I saw the oil pressure light in time and didn't hurt anything.