I generally use around 8 for my top scorer(s). Occasionally, Ill go to 10-12 for elite players that I think can score straight through a double team or against an advantageous opponent in the post season. 4-6 for a couple secondary options and 1-3 for players that have either high IQ/ATH/SPD/PER/LP but maybe miss all the components to be a decent option. That puts most of my teams in a total distribution 35-45 points so percentage wise that keeps anyone player from having too much distribution but still concentrates on the better players. It's also important to have at least two players taking threes but three or four players is better. Generally 6 is too many.
Im not one to tinker with my distribution during the season but i generally check once or twice throughout the season that my total number of threes taken relative to my total FGs is between 25% and 35% and that my distribution %s are generally where I want them (ie one player is taking way to much of it). You could spend alot of time optimizing your distribution, but I think you can be 90% as effective in less than 15 total minutes the entire regular season. For me, its not worth the trade off to be really in the weeds in this area.