For most of the rigs where I work, if we shut them off for any appreciable time, they won't start back up without a jump.
that's what I was always taught. If you shut the truck off, there is a good chance it won't start back up.
I did once have a supervisor who told me not to run my ambulance when we were posted in a town that didn't provide us with quarters. She said it was wasting fuel. I promptly ignored her directions, as she was in an office most of the day, not in a truck posted on a street corner.
One a nice day, when we are in a park, in the shade, yes, I will gladly roll the windows down, maybe even open the doors, and turn the engine off. But most of the time, if i'm not in quarters, my truck doesn't get turned off unless we are parked an ER or getting fuel. The risks of it not turning back on when we get dispatched to a 911 call is too high, based on past experience. Most of our trucks are not plugged in when they are out of service, and some have a bad habit of not starting up, especially on a cold morning.
If people want to complain about me wasting taxpayer dollar (and I did have someone walk up to me when my partner was running to the bank, because she didn't think she should be allowed to do that either), they are more than welcome to funding the construction of an EMS station, with a crew lounge, bunk rooms, and electronic shoreline.
Side note: we no longer leave our suctions plugged in, as we have found it typically kills the batteries, and renders it useless when we need it. once it starts dying, we replace it with a fresh one from the supervisors officer