I know it's petty of me, but it annoys me to no end when people label a tab in Excel "Summary" when it's actually a table of contents. Then they link all the other tabs to it (because it's a table of contents) so there's no way to rename it without breaking all the hyperlinks.
@CarrieLikesCoffee My Excel annoyance is people leaving extra tabs at the bottom because Excel created them as a default. They use only one sheet but leave Sheet2, Sheet3, etc. They also don't rename Sheet1.
@WordsmithFL I have legit created written instructions on pulling data where one of the first steps is to rename Sheet1 "Details" because of that.
@CarrieLikesCoffee I used to teach computer classes for various companies. I was able to design my own courseware, so I could address things like this.
I also showed them how to use the IF function to solve problems like dividing by zero and whatnot.