There are a lot of factors that affect how many schools you should apply to. I think the most important factor is how strong your application is (DAT/GPA/Experiences). It also depends how much money you are willing to spend. Do not apply anywhere that you cannot truly see yourself going. Sounds obvious right? But so many people do it every year. My advice is to create a list of schools that you'd be comfortable going to (based on cost, location, etc.), and narrow it down from there. Also remember that you'll have to spend time and money interviewing at each school. You can determine if your stats are competitive with each school's average as well. It's not a bad thing to include one or two schools that are considered a reach though. I would highly advise against applying to more than 14-15, as it is extremely time and money consuming to (A) fill out applications, (B) travel to all of the interviews. I feel like generally most people do 9-10. In the end, it's very hard to gauge without knowing what your application is like.