Nothing wrong with that used to be the norm back in the day when machines were expenssive and lobour was cheap.
The only problem comes with the drive belt slipping.
If it is a vari drive or geared mower it is fine cause those belts don't slip when the tractor is standing still so you can leave it there, engine running and brake on.
On hydro models you will have to chock the drive wheels so it can not move and leave the brake off.
#3
BlazNT
If you have a hydro drive I would remove the belt to the hydros because as long as the belt is moving you are using the hydro drive and waring it out.