Nobody chose Excel for lean. It became the default because it was already there. But there's a real cost to running a CI programme in a tool that has no idea what a value stream is — and most teams are paying it without ever adding it up.
Ask a lean coordinator to show you their CI system and most will open four or five files. A VSM drawn in Visio or on a whiteboard, photographed and saved as a PNG. Cycle times in a separate Excel workbook, with a tab for each process step. Root cause analysis notes in a Word doc or a Teams thread. A kaizen log nobody has updated in two weeks. An improvement tracker with RAG status that lives in someone's OneDrive.
Each file is technically functional. Together, they form a system where nothing is connected. When the cycle time at Station 4 changes, the VSM doesn't update. When a kaizen event closes, the improvement register doesn't automatically reflect it. When a 5 Why finds a root cause, there's no link back to the step where the problem lives.
This is not an Excel problem specifically. It's a fragmentation problem. Excel is just the most common tool in that fragmented system.
Every time you want a current-state picture — for a monthly review, a kaizen readout, a manager asking for an update — someone spends 30 to 90 minutes pulling numbers from multiple sources, checking that the VSM matches the time study, checking that the time study matches the current standard. This is not improvement work. It is maintenance work caused by fragmentation.
By the time you have reconciled your data and produced the report, the process has moved on. The cycle time you measured two weeks ago reflects the line before last Thursday's changeover. The kaizen status you reported was correct as of Monday. Improvement decisions made on stale data produce stale improvement.
When a lean engineer leaves, their improvement history goes with them. The context for why Station 4 runs at 142 seconds instead of 120 is in their notes. The reason the Fishbone analysis in 2024 pointed to fixture wear is in a file named "5why_station4_v3_FINAL_revised.xlsx" that may or may not be findable. CI programmes that live in spreadsheets are structurally dependent on the people who maintain them.
A root cause analysis that lives in a separate document from the VSM step where the problem was found produces no automatic link between the finding and the countermeasure and the measurable result. You cannot close the loop without manual effort. Most of the time, the loop doesn't get closed at all.
The difference is not features. The difference is a single data model. When your time study, your root cause analysis, your kaizen log, and your value stream map all live in the same system and reference the same process steps, several things happen automatically that currently require manual work:
Excel is the right answer for one-off analysis that doesn't need to connect to anything else. An ad hoc capacity calculation. A quick cost comparison. A pivot table on export data. For tasks like these, Excel is fast and flexible and there is no reason to use anything else.
The problem is using Excel for the parts of CI that should connect — the VSM, the time studies, the root cause work, the improvement tracking. Those parts need a system, not a file.
The biggest barrier to switching tools in manufacturing is not capability — it's inertia. The team knows the spreadsheet. The spreadsheet exists. Starting over feels like admitting the old way was wrong.
The practical approach is to run one project in the new system and leave everything else alone. Pick a process that has an upcoming improvement event — a known bottleneck, a quality issue with a root cause you haven't fully addressed, a changeover that keeps slipping. Map it in VeSiMy, run the time study there, do the kaizen tracking there. At the end of the event, generate the A3 from the tool.
If the report takes ten minutes instead of a day, and the data is current instead of two weeks old, the case for the rest of your projects makes itself.
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