Cancelling SARTIME through NAIPS is not sometimes a good idea. Especially at a flying school.
Sortie 1 goes out at 0700 for an 1100 return. Before then, the next student submits a plan for sortie 2 in the same aircraft.
Student from sortie 1 lands looks up VH-XXX on naips and cancels the sartime.
Result, wrong SARTIME is cancelled.
# 1 remains open and expires
# 2 departs but doesn't know his SARTIME and plan have disappeared from the system.