I think every college asks visiting students to register, and so the names are on record. I don’t think that “interest” is immensely important, but I think absence of it can tip the scales at “second-tier” schools. Most students cannot visit colleges physically, of course, but - in this digital age - it is very, very easy to demonstrate interest. Go to a college’s website, identify your regional admissions representative, research “road-shows” in your area. Highly competitive students probably won’t have free time to meet an admissions rep or alumni/ae interview in the fall of their senior years, but they will all have the time to send an e-mail inquiring about alternative times or simply saying how sorry they are that they cannot attend. Find some intelligent, meaningful questions to ask the admissions office. I see too many students lamenting their disappointing admission results after “shotgunning” the “Top Twenty” (or thirty) colleges. I think some of those waiting-list spots might well have been acceptances if the student had invested a few more minutes communicating with a shorter list of colleges. That’s pure hypothesis on my part, but I had a son punch slightly above his weight last year, and I attribute it to his outreach efforts. The one surprise was University of Washington, which was one school where he had not demonstrated interest. He didn’t get in everywhere, but they all knew he was serious about them.