Standbys are often used in cover scheduling
In certain periods one or more teachers are on standby, i.e. they are readily available for possible substitutions. The standbys are scheduled after the timetable is completed. The following points need to be considered
•The standbys must be distributed evenly among the teachers.
•In certain periods, e.g. the first period, more than one standby is needed.
•There has to be a limit of how many standbys a teacher can be assigned to.
•The standbys have to "fit in with" the regular timetable of the teacher. The teacher should not be assigned lessons while he is on standby, of course. On the other hand the standbys should not be scheduled on (half) days without regular lessons. Ideal are non-teaching periods between two lessons or periods that are adjacent to lessons.
•Several standbys on the same day are generally not desirable.