Ah dusting....Since these are all in the man cave, that task falls squarely on me. the wife seldom does anything but stick here head in the door when we are gaming and she won't touch anything!

So, I do it the quick and easy way with canned air and my shop-vac. Spray the models with one hand while holding the vac nozzle in the other.
It works great except anything that came loose from use tends to get blown off and sucked up. Checking each model after a gaming session has reduced that to a very rare occurrence.
As for the size of the collection, I've been building models for almost 50 years. Most of the 1/35th scale collection was sold off yeas ago prior to a move, but the stuff we can game with on the table-top remains.My Battletech collection is equally as large, but seldom sees much use anymore. Only my larger N-scale mechs see any table time. At my age, the smaller 1/285th stuff is just too hard to see and keep track of on an 8' x 4' table.