Problem :
It would be good to display how much time you have in use (% wise) in your schedule. When an appointment is added/changed/deleted for each resource it will calculate the appointments on the days that have been changed against your total time available and get a % which will be added to the top of the schedule. When you have less than 50% available it will show yellow and when you go over 50% it will show in red.
Solution:
You can utilize the SchedulerControl.CustomDrawDayViewAllDayArea event to draw this statistics in the All-Day appointments area. Then, you can collect appointments for a particular day using the SchedulerStorageBase.GetAppointments method. To calculate work time loads, use the DevExpress.XtraScheduler.Tools.IntervalLoadRatioCalculator instance.
This following picture shows the resulting application.