Yup, 5 mins here too unless i have a lot of stop/starts to do. Not too sure how many stop/starts my battery would cope with in a short period of time. esp with a 15-30sec pre heat before each whirl...
Also, I prefer to shut down the engine and leave the tractor in gear to act as a secondary failsafe just incase the parking brake let go or were pushed by accident...
Besides.... wouldn't you prefer to smell pine trees instead of diesel exhaust fumes...?