My children attend Mercersburg. They have family style lunch with assigned seating M-F. They have formal dinner on Monday nights and seated dinners Wednesday and Thursday night. All other meals are buffet. This winter I think they had a little more flexibility on The non-formal dinner nights.
They usually have a school meeting in the chapel or the theatre on Fridays and sometimes Monday evenings for speakers.
We have had a great experience so far! Please let me know if you have any questions. It’s a wonderful school community!