How long will strings last in their packaging? I assume they'll last for quite some time, yes? LR's tend to go for $26+ at Guitar Center, but Just Strings has them for about $22 excluding shipping (which is about $6) so I'm considering purchasing five sets of DR Lo-Riders (SS) to save money on the shipping. I change my strings every 1.5-2 months... would it be fine to leave 3-4 sets of strings just sitting around? I assume it wouldn't be a problem, but I just want to confirm that before I shell out a fair amount of money.