The plan is agreed Friday. By Monday afternoon it’s been rewritten. This happens so consistently in so many plants that it’s treated as normal — an unavoidable feature of manufacturing rather than a symptom of something specific and fixable.

The Four Usual Causes

The plan was never feasible. Built from theoretical capacity, ignoring changeover time, assuming full attendance and no breakdowns. A plan that requires everything to go right is guaranteed to fail, and everyone on the floor knows it before the week starts. If your planners are routinely loading above demonstrated capacity, the plan is a wish list.
Materials weren’t confirmed. The plan assumed availability based on system stock or a promised delivery date. Neither was verified. A component is short, and the sequence collapses around it.
Sales made commitments outside the process. An urgent order arrives with a date already promised to the customer. It has to go in, and everything else shifts. This is a governance problem, not a planning one — and it recurs because there’s no agreed mechanism for saying yes to urgency and no to everything it displaces.
The plan was too detailed too far out. Sequencing every job three weeks ahead guarantees rework, because the conditions those decisions were based on will have changed. Detail should increase as the horizon shortens.

What Actually Fixes It

Plan to demonstrated capacity with a deliberate reserve. Loading to ninety percent of what you’ve historically achieved feels like leaving output on the table. In practice it produces more finished goods than loading to a hundred and ten percent and then thrashing, because the reserve absorbs variability instead of propagating it.
Confirm material before you commit a job. Not system stock — confirmed availability, including anything in quarantine or reserved elsewhere. A job scheduled without confirmed material is a placeholder pretending to be a plan.

Freeze a window. Nothing changes inside a defined near-term period without an explicit trade-off decision and a named person approving it. This doesn’t mean refusing urgent orders. It means making the cost of accepting one visible at the moment of acceptance, rather than absorbing it silently on the floor.
Match granularity to horizon. Firm sequence for the frozen window, planned but flexible for the next few weeks, aggregate capacity beyond that. Planners who sequence in detail six weeks out are doing work that will be discarded, and the time would be better spent verifying materials on the near-term jobs.
Give the floor a route to push back. If a supervisor knows the sequence won’t work, that information needs somewhere to go before Monday rather than being resolved silently with a resequence nobody records. A five-minute Friday review with the people who’ll run the plan catches more infeasibility than any validation rule.

Measure Whether it’s Working

Track schedule adherence — the percentage of jobs completed in the planned period, in the planned sequence. Most plants have never measured this and are startled by the first number. Track it weekly, look at the reasons behind misses, and fix the recurring ones. The reason codes are more valuable than the percentage.
ticktick.ai builds schedules against confirmed material and demonstrated capacity, and records the reason whenever a job moves — so the pattern behind the breakage becomes visible.