I also encourage being realistic. How far would the commute to the school be? Can you really afford the tuition? There's no point in applying to 8 schools if it realistically won't be affordable or your kid will spend 90 min+ a day commuting in DMV traffic.

If you are coming from a Catholic K-8 with good scores, I think 2-3 is plenty, especially if one is something like BI or O'Connell. My DS applied to BI and more of a reach school and that was plenty. It's also possible to kind of rework essays to fit different applications so you don't have to write so many from scratch. Good luck!