I once got called in to diagnose why it took 5 minutes to open up a single Excel file. The PC itself was a little dated and underpowered, but the file size was huuuge…like hundreds of MB.
It finally opened. There was ugly table-formatting…to the entire spreadsheet. Colored cell borders, alternating background fill, text and font formatting applied to every single cell; columns A-IV and rows 1-65,536. I pointed that out and said the only way to fix is start a new one and not apply the formatting, or to try and remove it from all the cells. She outright refused because she liked the way it was. So I left, and she went back to looking at pictures of her cats
Sadly, the average person has no idea what this is or what it means