Seems like this friends advice is along the lines of this: Since the truck just sits for long periods, the oil drains to the bottom of the pan. So every single time it is started it's a "dry start." I think the friends point is that since it is going to be a "dry start" every single time, starting it less often would be better on the engine. Therefore the advice to only start it when "you really need to use the truck" and not weekly "for a short trip or errand," when one of the other vehicles would do.

I understand his thinking, but it's not logical. Whichever car was used for the "short trip or errand" would be getting a "dry start" since the oil drains to the bottom of the pan overnight. Maybe better advice would be to figure out which 2 of the 3 vehicles you really want to keep, then put a little cash into the ol' savings account by selling the other one and eliminate having a third vehicle that just sits in the driveway for extended periods of time.