I had a really long, detailed response that i thought I sent. Looks like I didn't.
The short of it is that you want the higher usage guys to be your extremes. If the guy most likely to take the field goal attempt is most likely going to take it from the range that falls into what most owners leave their defensive positioning set to because it's wonky as hell... That's not helping the cause at all. Don't get me wrong; threes help no matter what usage, but two of your top three usage guys should be opposite extremes. I went through all 8 of my draft league champions to demonstrate this, but apparently I didn't hit submit, I'm not repeating that effort. My ideal setup is something like this:
highest usage: 60%-90% paint scorer
2nd highest: 35%-45% perimeter
3rd highest: 25%-45% perimeter
4th highest: 40%+ perimeter
5th highest: 60%+ paint
(where none of the guys have a higher mid% than paint + perimeter)
(the last two can be swapped)
Do that (with low PF & high FTA/poss on the highest usage guys), and it'll go a long way towards giving you the best chance to consistently win the free throw battle. Again - we're talking chance & statistics, though.