We have a similiar system with kwikset. When residents move out we put in a core that is keyed to all other vacant units. That way when contractors come to clean or paint or do carpet we give them that key. It is also the same key that gets you in all entry doors. The problem comes up when you have little random locks for garage doors, gates, mail boxes, cable locks, etc. I probably only have four different keys for dead bolt style locks. The other are odd locks that don't take that type of key.
Yeah, Schlege has a relatively new keyway system available, too. They call it "Primus". It even requires a special key cutting machine to cut the keys, but it also has all the attributes of the Best and Kwikset systems.
There are plenty of options available for large property owners to limit the number of keys a property manager or maintenance crew have to deal with, and to streamline the the rekeying process, with out disassembling or replacing the lock.
Running around with a load of keys is not only antiquated, but it's actually pretty costly, and time consuming, and not efficient, at all.
I have 2 GM trucks and 3 Rams, I have one key that operates everything on both of the GM trucks including the ignitions, doors, glove boxes, consoles, tailgates, and tool boxes, and one key that operates everything on all of the Ram trucks the same way.
I also have 5 properties, with countless locks and even pad locks, and the third key on my key ring operates every lock at all the properties, including pad locks on the shop doors.
I can also give a person a key to any of my trucks, or properties that will only work that particular truck or property. I refer to that key as the "Service key". It wasn't a difficult or expensive process to set that up, either.
GM offers a lock cylinder that comes "unkeyed". They have them for ignitions, doors, tailgates, glove compartments, consoles, even tool boxes. To key them, you select the key you want to use, and the first time you put the key into the cylinder, it keys the cylinder to THAT key, only.
It was a little more difficult with the Rams, though, I had to take two of the trucks to a lock smith to have them keyed to the first truck. That lock smith also used MoPar lock cylinders to adapt the tool boxes ( not Mopar built-ins) to the Rams ignition key.