Mechanically it doesnt make any difference. Safety wise, it might be better to take it out of gear also. When I park my Yanmar 4220 for any reason that I leave it running, I lower the FEL bucket hard down so it raises the front tires a bit, just so it doesnt wander off just for safety sake. It is so easy to bump the shift lever when getting back on. Whenever I park it, I take it out of gear for safety since mine will crank with it in gear and without clutch depressed. I just keep the habit of shifting the gear shift to neutral just in cas the powershift gets left or bumped into gear. As for idleing times, I will shut mine down if I am going to be off it for more than a few minutes. I dont think you will hurt a diesel by letting it idle, it will blow out a bunch of carbon when you rev it up after setting for a while idling, so it does carbon up a bit. Truckers leave them idling when they stop for meals etc and those with sleeper leave them idling all night while they run the AC to keep cool so I would say as for idling, not problem. We used to have an old D17 Allis Chalmers that never would start right and had to be pulled off nearly everytime. We pulled it off every morning and it ran till we quit at night, sometimes idling for more than an hour at lunch. Never hurt it any.