Foam padded cases were never designed for LT storage. However, I use a gunsock which is supposed to move moisture to the outside and foam padded hard cases for over 20 years w/o incident. But everything gets inspected 2X a year.
Yes, I am just a "random sample of one" for the stat faithful. I suspect a layer of oil does build up over the years and this may be the secret of my success.
Lately, I've been adding the desiccant that comes w my VA meds to the cases. Not sure it does anything or not - too soon to tell one way or another.