It would be handy to see the "session number" on the appointment in the Calendar. When appointments are mass-scheduled, say 12 at a time, the client can easily miss a notice for a session. The trainer then has to keep a tally of sessions owed and it can be difficult when they're not labeled. Some long time clients have many sessions and reoccurring session packs so things can get confusing.

It would also be good to check for a client how many sessions they have left without having to go to the calendar and count.