A lot of the designer comments here make the designers sound like arrogant pricks.
Remember folks, it is your job to be the expert, and that means dealing with dolts with a smile.
Oh, and I have one for you....a story actually.
My third-line manager at IBM was using the first GUI and mouse, circa 1989. He was trying to move the mouse pointer way across the screen and ran out of room on his desk to move the mouse...so he held up notebook and teetered it on his knee and moved the mouse from the desk onto that, repeating as needed.
Then, I showed him how to pick up the mouse and move it a couple of inches, repeating as needed.
And, we cleaned off a wider area on his desk.