My thing with the concrete poles is it is nothing but a dead ground, a giant series of steel re-bar with concrete surrounding it, hence why I treat the mechanical jumper just like I would any other bare conductor, a dry wood pole does offer some insulation value which I believe is considerably more forgiving, don't get me wrong I am not advocating not using rubber to cover mac's on wood poles I just don't believe you have to go to the extreme's that you should with concrete. As far as mac's being taken down every night that was not always practical for me as on re-conductor jobs I have left them on for a month or more, I agree the sun and elements do a number on them and I just make me up some more, also I would tighten them periodically if leaving them on the line for a while or you will be putting on some armor rods or sleaving the wire.