I have a 95 that stays parked at the Albuquerque airport for extended periods of time and I've never had any mechanical issues with her as a result of sitting for long periods of time. I do top off the fuel on the way to the parking lot and other than my usual keeping the truck on a maintenance schedule of replacing all hoses, belts, filters, fluids, etc., the truck hasn't suffered any known effects as a result of her being abused in that manner. Batteries have always been my biggest concern but the Optima Redtops seem to handle the intermittent use just fine. The truck has been used in this manner for well over 5 years now.
On a related rant, as a result of sitting in the open like that in a parking lot shared with TSA agents, the truck has taken a beating. The body was somewhat pristine when I first started parking there and over the years has been run into several times, doors opened on her, etc., and not once has anybody tried to contact me for the damage they've done. I'm as careful as I can be in terms of where in the parking lot I park, end of a row, max distance from other vehicles, etc., and the truck has still taken a beating.......I still greatly enjoy driving that truck and plan on never selling her. I bought the truck new in July of '95 and she now has over 300,000 trouble-free miles on her and still gets a steady non-towing 20-24 mpg in easy mountain terrain driving.