I really mean a keyboard shortcut. I often find it necessary to turn them off then right back on when looking out for one of those very, very dim little dots. I need the lines for positional awareness and the sense of direction and speed yet at the same time they often obfuscate the little dot. I could miss them entirely. Because it's so dim, it's important to retain a direct line of sight with it. Stuffing my nose in the RHP breaks the line of sight. A keybinding would not.
I'd have a use for it every time I find myself in an uncharted system. That is, several times per hour.