Spreadsheets and Data Without the Pain

• One row per thing, one column per attribute. No merged cells anywhere — they break every filter, sort and pivot.
• One value per cell. A column of 'Mon, Tue, Wed' in one cell cannot be sorted or grouped, ever.
• Never leave a blank cell where a value belongs. Use an explicit 'unknown' or 'N/A', so blanks mean something.
• Keep dates as real dates, in one format, not as text in four formats.
• Do not merge data into a presentation sheet. Keep the raw data on its own and summarise separately.
• Keep a lookup sheet for repeated lists, so 'Design' is never typed as 'design' in one row and 'Design ' in another.

• Find duplicates before anything else. They inflate every total and skew every average.
• Standardise the text: trim the spaces, fix the capitalisation, decide how missing values are written.
• Convert the date formats to one, and check whether any are ambiguous — 01/02/2026 is not a date in most of the world.
• Check the types. Anything summing to zero is usually text pretending to be a number.
• Decide what to do with blanks before you start, and write it down, rather than improvising per row.

The moment you start writing the same formula with a small change in twelve rows, you have outgrown the spreadsheet. That is the signal to move the data into JSON and work with it properly — and most of that work is now one copy and paste away.