On most floor pumps, there is a lever at the head of the pump that you lift up to lock it on the valve (for some pumps, it's the opposite: you lift it before putting it on the valve, then press down to lock). This process more or less bends or "abuses" the part of the tube at the valve area, especially if when the lever is not very easy to be put in the locking position. It seems frequent manipulations like this will subject the valve area to damage, causing leaking tube?

(One reason I'm concerned about this is that I'm undecided whether to pump the tires whenever it's not hard full of air, even if still plenty of air.)