Heres my take on it. First and formost the car has a great deal to do with it. With out a consistant car your really fighting a losing battle. Second, if its easier to leave off a bottom bulb why would we have tree blinders,crosstalk, etc. Cutting a good light off a top bulb is easier and more consistant. Period. Cutting a O or teen light is practice no matter which tree. The ave Supper Index car will cut lights in a closer range (.00-.015) than a ave footbrake car (.00-.040). Some are better ,some are worse. Look at the ave R/T times of different classes and you'll see. If you can't drive the finish line you won't win very often. You don't really think very many bracket racers dial ther car dead on,do you?
Doug