Queue is actually "extra work items in queue", that's why when using 0, staged work (ST) is still at 1. It was useful back in the days before stratum, but since now work is locally generated (LW) at will by cgminer, it only serves as a hindrance on coin switches, although it shouldn't be happening.
Weirdly I tried setting my queue to 0 in my 50-50 config that load balances between Clever and Middle, and my rejects went up a lot to over 10%. I set it back to 3 where I had it previously and now rejects are back in the 2% range.