I think this is a fair assumption to have but I genuinely do not think this is the case because they should (and I am sure do in fact) factor in many reasons as to why an applicant applied a little bit later compared to another. Also, applying early does not mean having the best application possible, so if you applied early but your application is not up to standards, it will be more appealing for them to accept someone who applied on the deadline but did submit an excellent application. I remember last year on the forum so many people got through some firms despite having applied on the deadline, and a lot of people who applied early were not successful. I think that, ultimately, the quality of the applications is what will set you apart and not when you actually submitted it, if that makes sense. This is my personal opinion though, who knows, you might be right!