Yes, you can "Completely disregard the octane selector", as brokenhead recommends, or you can use it to fine tune the optimum timing for your application after setting the pointer on the ball. The final optimum timing setting is confirmed by test drive. Needle on the ball may well be it, maybe not. I use the octane selector to fine tune so that I can experiment different settings, and have the ability to easily go back to the original setting without having to hook up the timing light every time I need to make an adjustment. You can do your test drive with a wrench in hand, pull over to the side of the road, adjust the timing with the octane selector, and test drive it again until it is just right. I would call that "a real use".
