someone posted a simplified view that was pretty similar in effect to my system, that i thought was a VERY nice way of describing a highly effective distro strategy (relative to the pool of distro strategies, which, on the whole, are not very good). OP - just a comment, distro is definitely the hardest thing to get down of setting your team up, and i encourage you to continue to build your understanding over many years, not to try to find a system that is "good enough" and sticking with that.
anyway, the guy im talking about said, i set my distro for each player, to the # of shots i want them to take in a game. i like that model - its easy to understand, and its more effective than the hundreds of tiered or otherwise simplified systems people use. its a bit simplified, and of course it wont actually line up exactly with shots, as players will turn the ball over, and get fouled/take FTs, instead of shooting - but thats still a possession.
what distribution really means is, if you look at the 5 guys on the floor, each one is going to try to get the ratio of possessions equal to the ratio of their distro to the sum of the 5 players' distro.
example: pg - 5 distro, sg 12, sf 10, pf 5, c 8. total - 50
the pg is going to get roughly 10% of the possessions, the sg roughly 24%, the sf roughly 20%, the pf roughly 10%, and the center, roughly 16%. over a long enough sample size, those numbers will get close - but keep in mind the engine is compensating based on things like, what is the defense running, +/- setting, who is defending who... nobody knows exactly what all the engine compensates for, but its stuff like that. also, note that distro does not govern things like quick putbacks on offensive rebounds, its really about who gets the green light when you are in the half court running the offense, if you will.
anyway, when you are done setting your distro, you should be able to look at it and go (using the same example), do i really want my sg taking about 2.5 shots for every 1 the pg takes? if yes, then thats good. if not, back to work! i think the # of shots you want a guy to take gets you most of the way there. usually my step 1 is to set individual distro with NO consideration for team or situation. then, i make adjustments for those things - for example, if im light on 3 point shooting, and have one single great 3 point shooter, they get bumped up, to protect me from heavy - settings.
because the distro system works off ratios, and its rare to have a bunch of players the same effectiveness on offense, where you really want some guys taking more, some less, i can't get behind any tiered system - not that they are all terrible, its just basically guaranteed to be sub-optimal in every case. also, i strongly recommend you DONT have your distro sum to 100, that presents a nasty overhead any time you tweak anything. my best guy on normal teams is in the 12-14 range, and then everyone else falls somewhere lower than that. that gives you a low enough total not to be worried about hitting 100, with big enough numbers to fine tune relationships between players.
hope that helps!