1. Fridays are the busiest days for us departure wise. 2. AA implements their schedule changes on the first or second Wednesday of the month and it actually doesn't change much, if indeed at all, week to week for the rest of the month. Friday vs Saturday vs Wednesday yes, but Friday vs Friday, within the same month, no. So I chose a representative day when we are flying at our peak in both months. 3 I don't have the time to go day by day and do all that math.

So to sum up I deliberately chose a Friday in the middle of the month on both months to make it as fair as possible. Its as far away from the monthly schedule changes as possible. It's also the third Friday of the month in both months.