Hi @mczchl! I would say 10 were very selective schools (~10% admissions rate). Five were less selective, but still good schools, where I applied for full ride merit scholarships. The last 5 were safeties where I automatically received (close to, if not completely) full rides, and I applied into their honors college programs.
As to your last question, it definitely depends on the person. If applying to 20+ schools will decrease the quality of your applications, then you should apply to less and devote more time to each to help your admissions chances at any one of them. I was genuinely interested in each school, so I was willing to take the time to create an application for each school, though it was an intense 3 months or so.