KenV - why don't you get hold of a couple of toy a/c and practice some formation? Even just use your hands. Then you'll see!
Good idea! Now try this:
Place both hands on a table top, side by side. Now raise both hands 3 inches above the table top. Lead is your left hand. "Roll" both hands 30 degrees to the left while keeping the centerline of both hands 3 inches above the table top. Without an eyeborw window, how does the pilot flying your right hand see his lead who is flying your left hand?
Did that help?