Spreadsheets Vs Post-It Notes

I’m a fan of documentation, over the years I’ve ended up supporting more than one business critical system that has less documentation than you get from a cat /dev/null.

The only downside, and I’ve been bitten by a couple of things like this over the last week is the case of the spreadsheet vs the post-it note - if you have a lovely, well formatted and information dense spreadsheet that says “A is 1” and when you get to the server room the switch has a post-it, in bad scrawl, that says “B is 2” which do you believe?