Actually, if you have a PIN, you really need to follow them. Americans are used to hitting enter until the slip comes up to be signed. However, if your card has a PIN it needs to be entered before that point or your transaction is rejected. It took me a few instances of having my transaction rejected to twig to this issue; now I tell them to slow down and give me the terminal to enter the PIN. (This was, I admit, pre-Covid and perhaps it has changed, but I doubt it.)