How long is a spreadsheet the right tool?
While one person enters the data, the same person reads it and the decision comes from that sheet, a spreadsheet is the right tool. It costs nothing, changes instantly and needs nobody’s permission.
Those same three properties draw its limit: needing nobody’s permission also means nobody knows who changed what, or when.
Which signs say the time has come?
Four are reliable in practice: the same data kept in two files, filenames multiplying with “final”, “new” and “current”, having to ask the person who built the sheet to answer a question, and nobody knowing how to repair the sheet when it breaks.
None of these is the spreadsheet’s fault. They all say one thing: more than one person now touches the data, and a file is not the tool for that.
Does everything have to move at once?
It does not, and usually should not. Taking every sheet into a system at the same time produces both an enormous scope and a change nobody can absorb.
What works is starting with the sheet whose errors cost the most. Usually that is stock or orders — where a wrong figure reaches dispatch and the invoice directly.
Should spreadsheets be abandoned entirely?
No. Even after a system is in place they remain a good analysis tool; what changes is where the data is born.
The right arrangement: the record is created in the system and the sheet is fed from it. The wrong one is the reverse — data entered into a sheet and transferred into the system later.