Hi,
In order to configure the reserved tickets according to my understanding there are two levels: global for the whole calendar and fine for each event.
On global configuration Parameters and Permissions iCagenda -> Registration there is only the option to configure MAX Tickets/Registration without any option to configure global the maximum number of tickets. In this case it is necessary to configure granular on each event the maximum number of seats.
I think such option could be a candidate feature for the next release having a global configuration and also a granular one per event.
Thanks,
Ion