Hi yes,
the way I've always used it is that when I want to toggle ortho in a command (for example when copying something or whilst making a polyline or spline) I hold shift until it toggles off/on. I don't just press it, because it never worked that way before either for me. You needed to hold it down to toggle, once released it would go back to normal setting. So I certainly hold it down long enough for any delay to be irrelevant. I've currently changed the short cut to Shift+z but it's just another key to press, first to toggle on and then you have to do Shift+z to toggle off again so it's not that convenient.. But it's better than to move your whole hand across the keyboard to F8.. As someone else mentioned, you can not set the short cut for ortho toggle to be only Shift.
I’ve attached an image of my key board and I’ve tried with the FN locked on or off, it doesn’t make a difference (apart from when using F8)