I just thought about another thing - older guitars with old style compression (i.e. not dual rod) truss rods will need some relief so that you're not constantly adjusting it with changing weather. Dual rod truss rods (like on my Ricks and W's) are not as sensitive with humidity changes and therefore just plain don't move around.
I was reminded of this after setting up my bass player's Jazz Bass last winter, only for her to complain in the spring that there was a big ass back bow in the neck (oooops). After that, I put some relief in the neck so that she does not constantly bug me about it :evil4: :headbang: