This goes into the same vein I was going to point out. Most uncontrolled space usage comes from logs, users doing user things, or something like build servers

This goes into the same vein I was going to point out. Most uncontrolled space usage comes from logs, users doing user things, or something like build servers just eating temporary and caching storage for lunch. Databases also tend to have uncontrolled space usage, but that tends to be wanted. So, if you push /var/log to it's own 20-30Gb partition, a mad logger cannot fill up /. It can kill logging, but no logging is better than fighting with a full /. Similar things with /home - let users fill up their home dirs and pout and scream about it... but / is still fine. And you can use their input to provide more storage, if they have useful workflows. Something like databases - where their primary use case is to grow - need monitoring though to add storage as necessary.