However, the behavior of the admissions committees suggest a more flexible approach. Anyone who gets their application materials into the program before the committees make a final decision will have their application considered by the committee. There is no program that wants to arbitrarily reject an applicant simply because their materials were late. All programs have a method to receive and deal with late applications. However, after the acceptance decisions are made, the committee is obviously unable to consider more applications.
Programs vary considerably in how they handle the late application.
If a program receives hundreds of applications, then the program probably has no flexibility with the deadline. The committee may well end all consideration of applications that are not complete by the deadline. The number of applications to such programs is already large and unmanageable and this policy keeps the numbers down. That being said, many programs with a large number of applicants are very thorough and review every application submitted, even those that are incomplete at the deadline. Unfortunately each program uses a different form and completing the various forms is time-consuming and inefficient.