Being repeatedly compressed and relieved is what wears out springs, not being compressed and left.
There are many stories of handgun magazines being loaded and untouched for 50+ years and still working fine.
Your shotgun being loaded for a few months or a year or two will be fine.
Besides which, are you really going to load a gun and never shoot it for years on end?
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.