I gave up sorting yonks ago, and decided my time is better spent creating renders.
So, here's what I do to keep sanity:

1.  Install in major categories - Humans (males, females, kids,hair), non-Humans (anthropomorphs,realistic,toons), Environment (plants, buildings, landscapes), Thematic (seasonal,genre), and  Physical Poses  (not MAT poses).

2.  Use Semidieu's ShaderWorks to add all the runtimes into Poser libraryprefs.xml

3.  Use Dizzie's Advance Library to visually sight all my content. ( if not using Semidieu's program, then have to go extra step of using P3DO Explorer)

4.  Use Tromnek's PRPCdaemon to load items directly from Advance Library into Poser 6sr3.  Very important to have step 1 done,or else Poser asks for content path each time.)

There, no more fussing over content organisation.  Just do the creating part.

(These are all freeware utilities, at this time.  Except for Poser 6, of course)

Eternal Hobbyist