Constraint recipe
This rule targets subjects where two separate lessons on the same day hurt pacing, for example two English sessions on Tuesday when you wanted Monday and Thursday. It is narrower than full weekly spread. Exempt double periods, labs, and workshops first. If the subject has only two teaching days available, a strict same-day ban can make the timetable impossible.
Key takeaways
- The rule targets two separate lessons of one subject on one day.
- Double periods and lab blocks need explicit exemptions.
- Few available days can make a strict ban impossible.
- Apply it after required lessons and clashes are valid.
What this rule is for
Some subjects should not appear twice on the same day unless the session is designed as a block. The rule improves pacing for regular weekly subjects.
It is not for every subject. Practical doubles, assessments, and intensive modules may deliberately place two periods together.
How it differs from full spread
Weekly spread looks at the whole pattern across the timetable. Same-day avoidance only blocks two lessons of one subject on one day. You can use both, but start with clear exemptions.
See the double-period recipe for adjacent sessions that should stay together.
What to do next
- List subjects where two lessons on one day should be avoided.
- Remove required blocks, labs, and double periods from the rule.
- Count how many teaching days each subject realistically has.
- Set a same-day preference or penalty per subject.
- Regenerate and review which subjects still repeat on one day.
- Relax the rule for subjects with genuine placement limits.
Common mistakes
- Applying same-day avoidance to required double periods
- Treating a spread preference as more important than room requirements
- Ignoring subjects that only have two legal teaching days in the week
Quick answers
Can this rule block a timetable?
Yes, if treated as mandatory while the subject has too few teaching days. Keep it soft unless policy requires it.
How is this different from lesson spread?
It is narrower. It blocks two same-subject lessons on one day, not the full weekly distribution.