Exceptions are not rare. They are the plant’s real product mix. A missing insert, a customer hold, a specialist who is the only person who can release a lot. The cost is not the first exception. It is the hour when the named owner is in a meeting that has no deputy, and the pile grows by three more tickets that all look urgent and none have a clock.
Service Desk Throughput treats “waiting on customer” with suspicion. Often it is waiting on us. Shop Floor Cadence treats the quality meeting the same way: a scheduled theft of the board unless a deputy is written down.
Unowned exceptions feel cheap because nobody invoices them. They invoice themselves as overtime, as a missed boat, as a night crew restarting a live job. Name the hour. Name the deputy. Size a small buffer if the specialist is truly scarce — Inventory Rhythm Clinic will argue about hours of cover, not about virtue.
If your exception log has causes like “busy” and “complex,” you do not yet have a log. You have a mood diary. Moods do not schedule. Minutes do.