This year was an anomaly with the Presidential visit and construction in Michie both limiting seats. Cadets were asked to indicate how many they thought they might need, then were issued ten reserved plus requested extras (maybe 13 was just The Knight's company, or my cadet's company didn't get the memo?) -- one cadet requested, and got, 122.
Because of construction, many seats had little or no view of the stage. It was announced a day or two before graduation that all tickets had been distributed, and there were no "walkups". But cadets and parents managed to ask around companies or Facebook page and seemed to get all needed tickets.
In other years, families were given ten reserved with cadet's company plus pretty much unlimited extras elsewhere in the rest of the stadium.