Techniques for scheduling a task include receiving task data and quorum data. Task data describes tasks to be performed by one or more participants. Quorum data indicates a participant set of one or more participants to perform each task. Current user data may also be received. Current user data describes a current task set of one or more tasks currently being performed by a particular participant. Either or both of the task data and the current user data describe interruptibility through a particular medium of a plurality of communications media. A particular time interval to schedule a particular task is determined based at least in part on the interruptibility of the task or the particular participant. These techniques allow either or both unscheduled tasks and previously scheduled tasks to be moved to time intervals that overlap other scheduled tasks, including tasks currently being performed by a participant.