Schedule generation places default events (Back Office, Lunch, Break) before productive events fill the remaining gaps. When a default event lands partway into a productive block, the generator can only fill the resulting sliver, and it cannot move the default event. You can then see 15 to 30 minute productive blocks as a result, but agents need a minimum of one hour to be useful.

A conditional constraint: if there is productive time before or after a default event, that block must be at least X minutes. If there is no productive gap, meaning the default event sits at the shift boundary, the minimum is waived.

Expressed as a rule, this is a "at least X, or exactly zero" disjunction, which none of the current default event constraint types can express.