Adding my two cents here as another parent whose child went through the process last year. She researched about 30-35 schools, visited about 13, and ended up applying to 6. Those 6 were the best-fit schools for her. She really thought about what she wanted in her high school experience and what was important to her in terms of academics, social life, support, overall experience, etc. Then she actively researched with those things in mind. At the end of her research, she only had one GLADCHEMMS school left on her list. At the end of her visits, they were all gone! They just weren’t the right fit for what she wanted.
I think she was so successful in her admissions last year (she was accepted to all six schools) was because it was clear she had done her research and had things at each school that pointed to what she really wanted. The fit for her was clear to the schools in their review process.
I will say, she had to do four of her interviews virtually and it was so hard for her to establish a connection. She did much better with her in-person interviews. I say this to ease your fears over a bad interview perhaps “ruining” your chances at admission. One of her interviews was 20 minutes long and she literally said she had no questions when asked at the end. 
That’s like the one rule of interviews - you always have questions prepared (and she did - this was her last interview and she had done well in all the others). The interviewer also asked if she had anything else she wanted to share . . . she said no. She hadn’t covered any of her extracurricular interests or achievements at all. She just completely forgot all the prep she had done! And, she was admitted to that school even though she barely showed interest in the interview. So, it’s not the end if you make a mistake.
Something that the admissions people at a lot of the schools spoke about was our daughter’s kindness/character that was clear from her activities and her recommendations. I think that probably helped a lot. Her current dorm parent has also called that out on her report cards each term.