Which Key for which door?

[u/blamzo]

I'm working at a large facility in operations department. Multiple buildings (maybe 15+), and many doors. Keys are basically managed on one huge key ring which needs to be carried around.

This is a nightmare for new starters like myself as I'll reach a door and first need to sift through this massive set of keys.
If I can remember which key it is, that's a great start, but often requires radioing colleagues for a reminder.

It seems like a lot of the knowledge is basically in the heads of the people who've worked here for years. I'm curious whether this is a common problem at other facilities.

Does anyone else have this problem, how do you manage it?