Multiple passes when searching discs

I've searched the archives and the help files, but I haven't been able to find an answer to this very basic (I think) question:

Why does CDJ make multiple (typically 3, but sometimes 2 and sometimes 4 or more) passes when searching for discs (in either empty, empty/missing, or tedious modes)?

What exactly is it doing, and why does it seem to find certain discs on the first pass yet find other discs on later passes. Also, why on the last pass does it usually seem to do nothing physically with the changers but appears to zip through the discs in the CDJ search status window? In essence, why can't CDJ find everything it needs to find in a single pass?

If it matters in terms of answering my question, I've got ten CX-300s connected to one Slink-e, and I'm running the 4/11/00 version (Build 1841) of CDJ.

Thanks for your help,