Residential mowers will last a long time (as you can see from previous post on this topic) so long as you maintain them. Large business as well as small use the commercial do to the abuse and long term use that the mower is subjected throughout the day. (I have both residential/commercial equip.) I am a solo operator and baby my equipment and take care of the maintenance. I don't think an employee would "baby" my equipment. You keep any equipment properly maintained, it will last you a long time.
3 lawn mowers
1 walk behind edger
2 BP blowers
1 multi tool w/ hedge trimmer and edger attachment
1 broom (worn out needs replacement soon)