I agree this method does not look complete. I see that it is not referenced anywhere. I looked at the history of the file and noticed when it was written it never got used. This leads me further to believe that it is not a completed method. You might try the method GetForPeriodList(). That will essentially give you the same results you would get from GetAppointmentsForPeriod(), the main difference being that unscheduled and planned appointments are excluded.
The best thing about a boolean is even if you are wrong, you are only off by a bit.