Keeping drives cleaned up and organized is a good thing. You always know where stuff is and that it is most current. I've started putting what I consider archive files on CD. The Archived files are ones that I don't need except as historical references. The files can be data from old programs as one example. You want to keep the numbers as reference, but it doesn't need to be on the shared drive. I think the oldest was more than 5 yrs old, but I did refer to it in 2008.
S: drive I've used this before when submitting files to be printed at Admin. I like that it is supposed to be self cleaning if you forget to delete your file when done.
P: drive This is nice because you can access it even while logged on to a branch or generic profile. You can have files that are shared for informational or cooperative reasons. e.g. The computer class schedule is in this folder but that flyer we are working on is in this one. Organization using folders is a great way to put like documents together - supplies, periodicals, second floor stuff. Folders help when you are searching for particular documents - it is in the 'Friends' folder in the subfolder 'price tags'- instead of searching through many documents. Be careful of duplication and do you really need a copy of that form when it is on Harriet?
I'm looking at what I've made to be sure it is current and and not extraneous. I might make suggestions to a coworker if some reorganization would help everyone see the folders/files more clearly.
Z: drive This is accessed only under my profile. I keep track of expense documents, time sheets and my training hours here. Timesheets are current and two past. Once I check the County records, I delete mine. Training is current & last years to be sure I don't repeat something. I think I keep this one pretty clean since it is just myself.