This is probably so stupid a question that no one will respond, but just having gotten back into fly-tying after a long absence, I'm curious about what "systems" more experienced tiers use for organizing excess fly inventory tied during off-season. Before I tied I just bought what flies I needed, usually from local shops on site, so storage was just in my carried fly boxes. However, now tying a considerable inventory in anticipation of the upcoming season, it's obviously impracticable to store them all in my vest fly-boxes.
I recognize that some manufacturers offer modular "suitcases" holding a number of fly box interchangeable inserts which would address this situation. However, these all seem to require use of that manufacturer's proprietary fly-boxes, and the ones I've seen I don't care for as being too bulky.
The two "systems" that come to my mind are either large boat-type fly-boxes storing all my excess fly inventory in some sort of order, or a large collection of my favorite fly boxes (which are pretty small, since I fish mainly tailwaters with #18+ flies), either filled with the same fly assortment, be it nymphs, emergers, dries, etc., or more likely a mixture organized by time of season so that instead of re-stocking my vest boxes, I'd just replace the entire box with a suitable one from my inventory.
(I must say, after re-reading this, the thought "I need to get a life!" comes to mind