I'm not sure if anyone knows the answer to this question. It could work that way or it could work some other way.
Maybe applications are assigned to staff for verification based on the applicants last name (or some other criteria). If you're an "H" and the "H" reviewer gets your application at 10 am but still has three other applications before yours, than you're #4 in line. If the person who submits at 10:30 am is an "A" and the "A" reviewer has no applications at the moment, then they're #1 with that particular reviewer and their application will probably be processed before yours. I'm not suggesting this is how it works, but it could be. Or, maybe someone actually knows the answer to this question and I just waisted a lot of time (mine and yours).