When sawmill planners talk about “optimizing” production, they usually mean making the best decisions for the next shift or the next day. This feels rational — you work with what you know, you keep things manageable. But this approach has a hidden cost that compounds over time.
What is the local-optimum trap in sawmill planning?
Consider a simple example: you have two production lines and a mix of log grades coming in over the next two weeks. Each shift, you allocate the best-fit logs to keep both lines running at maximum throughput. The shift ends. Recovery looks acceptable. You do the same tomorrow.
What you can’t see is that the log grades arriving in day 8 would have unlocked a yield improvement of 4% on Line 1 — but only if Line 2 had run a slightly different pattern in day 3 to prepare the right intermediate stock.
By optimising locally, you’ve permanently closed off a globally better path.
“Optimizing each shift in isolation looks efficient — but it systematically prevents your mill from finding the globally best plan.”
Why does horizon length matter more at scale?
At 50,000 m³/year, the effect is modest. At 200,000+ m³/year, the compounding cost of local optimisation is measured in millions of euros annually. Not because individual decisions are wrong — they’re locally correct — but because the search space for a better global plan was never explored.
What recovery uplift do longer planning horizons deliver?
Across mills we’ve worked with, extending the planning horizon from shift-level to 2–4 weeks consistently improves lumber recovery by 2–5 percentage points.
| Planning approach | Typical recovery range |
|---|---|
| Shift-by-shift (manual) | 58–62% |
| Day-ahead planning | 61–65% |
| 2-week horizon optimization | 64–68% |
| 4-week horizon optimization | 66–70% |
Figures are illustrative averages across softwood operations in Northern Europe.
What Multi-Horizon Planning Actually Does
A multi-horizon planning system holds three timescales simultaneously:
Operational (1–3 days): Detailed shift-level sequences, specific log-to-product assignments, line changeover timing.
Tactical (1–2 weeks): Batch composition, grade allocation, stock build strategy, maintenance windows.
Strategic (2–4 weeks): Demand fulfilment sequencing, log intake pacing, product mix alignment with order book.
Each level informs the others. The tactical layer prevents the operational layer from making locally optimal but globally destructive choices.
The Constraint Interaction Problem
Recovery isn’t just about log quality. It’s about the interaction of constraints:
- Log grade distribution across intake windows
- Product specification requirements from the order book
- Blade wear patterns and maintenance scheduling
- Drying capacity and kiln sequencing
- Intermediate stock levels between production stages
Manual planning handles each of these sequentially and approximately. A constraint-aware optimization engine handles them simultaneously and exactly — within the bounds of what’s computationally tractable.
Practical Implication
If your mill currently plans one shift or one day ahead, the path to better recovery isn’t better shift-level decisions. It’s extending the horizon over which decisions are coordinated.
The first step is usually visibility: knowing what logs are arriving when, what orders need to be filled on what timeline, and where the binding constraints actually sit. The second step is optimization over that extended horizon — which is why the choice between spreadsheet-based planning and dedicated software matters more than most mills expect. We examine that gap in detail in our comparison of Excel-based planning versus dedicated sawmill software.
Both are tractable problems with the right tools.
Related Articles
- Why Planning Horizon Matters More Than Most Sawmills Think — the operational consequences of short-horizon planning and how extending it changes yield outcomes
- What Long-Term Sawmill Planning Actually Gives You — the business case for multi-week planning horizons and what mills report after making the shift
- What Sawmill Optimization Actually Means — a layer-by-layer breakdown of where yield gains come from, from log sorting to production planning
- Excel vs. Sawmill Planning Software: Where Manual Planning Destroys Margin — why spreadsheet-based approaches cannot find the global optimum, and what the cost difference looks like
SawmillSmart is a production planning and optimization system for sawmills. Learn more about how it works or talk to us about your operation.