I usually defrost my freezers once a year - every September. I'd read that it's a good thing - for the life of the freezer - to let it totally defrost, like maybe 24 hours, to let the freezer walls thaw too. And I did say "freezers". We used to have three, two of them, uprights, we got used, so who knows how old they were/are. Now we're down to two.
My garden and cookbook shelves are above the freezers
When we moved to Colorado from Arizona, Monte made this large insulated box so we could bring his hard-earned game meat (bow-hunting). That was twenty seven years ago, and we still have the box. I've stored jarred things in there in the garage for years. Now our garage is insulated so things don't freeze, but I still store some things in the box. Then every September it's moved by the freezers so I can defrost them.