In my opinion, FB utilizes more playmaking (ath, speed, ball-handling), like motion, which FB reverts to when not in transition (which doesn't mean you need to practice motion, or anything, just that the scoring algorithms are similar). Flex and triangle utilize more shooting (LP and PER) and passing. Going all -2 with FB is one way to do it, but probably not the best way as you move up divisions. Being one-dimensional is always dangerous, no matter how good you are. So I do find having a few per shooters for FB (as with motion) really helps open it up. I always try to have at least one guy who I feel good about setting to 0 or +1, to burn an opponent who abdicates the perimeter.
I know there are other ways to look at it, but I generally don't worry so much about how even distribution is, or how many scorers I need for a given set. I set distribution based on 1) who is a good scorer based on attributes/IQ weighted for my set, and 2) where my opponent may be vulnerable. Slow bigs do have trouble scoring efficiently in FB, but fast (relative for division) bigs can be very effective. Jason Terrell was player of the year from the PF position.
https://www.whatifsports.com/hd/PlayerHistory/Stats.aspx?pid=3306771