I think they have to go through everyone's application first before they start going back to the "on hold" category. I had received all other secondaries from the UCs over a month ago, and for some strange reason I just got UCI's last week (I was an August MCATer). I called them up, and they assured me that I wasn't at a disadvantage by taking the August MCAT, or by turning in the secondary this late...so, I can only assume they must put a significant portion of people on hold, just in case they find better fits in later applications...