For nonbelievers, here is a simple test you can perform in the privacy of your own garage. Fill the tank to the full mark (hot), then ride the bike as you normally do. Check the oil level weekly, but do not add unless the oil drops completely to the ADD mark (hot). If your bike is like many of them, what you are likely to find is that you will use about a pint of oil initially, then the level will stabilize at roughly halfway between the ADD and FULL marks. If this is the case with your bike, then it makes sense to just fill it only to that point in the first place. Unless you really think it's good to oil the air cleaner and throttle body/intake manifold, of course. Since these things aren't two stroke engines, I don't think it's necessary to pump oil through the intake myself.
If you somehow managed to get a Harley that doesn't puke out a pint initially, then by all means run it full.
Jerry