There are so many situations you can't predict and that aren't transparent. One is the speed of the reviewers. Some reviewers get assigned 34 applications, crank through them at a rate of 3 per day and finish ahead of their assigned 2 week deadline. Meanwhile, as those applications dribble in, the applicants can be queued for ii. That means that one equally good applicant might be 10 days ahead of another just by luck of the draw. There are dozens of ways to prioritize 34 applicants. You could take them in the order they were assigned, which might be alphabetical by last name, or by the date that they were complete, or your reviewer might choose high MCAT first, or URM first, or feeder schools first, or alma mater first, or any idiosyncratic way of slicing and dicing. Every reviewer is different and you have no way of knowing... I don't even know how my fellow reviewers might approach their virtual stack of applications.
On the other hand, you might be unlucky in being assigned to an adcom member who is overworked or overwhelmed or otherwise sits on the applications for 2 weeks past the deadline thus putting you, the unlucky applicant, 4 weeks behind someone who had the good fortune of being reviewed on day 1. Now you are a month behind someone through no fault of your own and for no reason.
Frankly, we'd expect that the superstars are interviewed early and quality declines over time. However, there is little decline in quality over time, at least at a top 20 school. YMMV
