Nope, just talking about brevets. I can only think of one or two in the last twenty years who've DNF'd because they went the wrong way. Most people figure out pretty quick if they went the wrong way. I guess if you are directionally challenged you might need one. It's really not that difficult to read a que sheet though. That's what we did for many years before GPS with no issues. Yes a tool is a tool, your car is a tool too but you don't use it to do brevets.