For me I let her warm up 5 to 10 minutes at 1000 rpm's before going to work.
If I'm using it I let it run, off and on to hook up to a log, adjust the top link, potty break, water break, change implements, etc.
If I plan to not use it for about 10 minutes or more then I switch it off, For this time when I crank it the temp gauge returns to normal pretty quick.
L4600 year model 2012 so no emissions to worry about.
I'm not a engine guy but just seems to me letting it idle at 1000 rpm's, low idle for me is 750 just seems it would cause less wear than shutting it down and cranking it every time I'm off and on it. I work alone so in a 10 to 12 hour day on the farm I'm off and on it a lot, 5 minutes off here and there all day.
Be interesting to hear from a diesel engine mechanic what his or her opinion is of this question.
Good day friends.
Jay