What are "real world" reasons why applying to a desired yet competative college/university needs to occur by or before starting the senior year of High School?

Answer 1

Some students are high achievers so they want to get into college early. The best thing for you to do is to volunteer in your field and prepare for the SAT. You can even get your general ed courses out of the way at a community college during that time.

Answer 2

There is no reason why a student must apply to a college before they begin senior year. Admissions officers do not begin reading applications until their travel season is over and after the deadline passed. Submitting earlier than a deadline will not put a student at an advantage.

Your junior year and summer before senior year should be dedicated to creating a solid college list and doing summer programs, pre-college programs, working or volunteering.