I was given several lockable filing cabinets, but no keys. Not a problem, went to the biggest locksmith town with the file brand name and the number on the locks, $5 each walked out with keys for all of them! I guess you could do that in almost any file room!
My family used some unbrand lock (all keyed the same) that we could buy by the dozen! We used 2 different keys depending on it was farm or construction. Since I got out of High School in 1974, If I see one of that type of lock in Central Ohio, I give it a casual try, My two keys fit about 2/3 of them, there must be a 3rd key I don't have.
When I started doing environmental clean-up, we lock everything we can up! We Use a "programable" combination lock by Master. Each jobsite has a new combo! We use something the whole crew can remember: Ammo Numbers have worked great. 3006, 4570, 4440 & 3840 were two gates n same property. For my personal locks I have two numbers: If I want my wife to get in it, her birthday, If I want to keep her out, my birthday. Maybe too simple, but we trust each other! I have about 20 of these locks and reprogram them as needed, when not "in use" they revert to her birthday.
Ivan