I'm confused. Why would you not want the largest boards possible, other than transportation issues? Cutting the tree into the largest, longest boards gives you increased choices about which end (or middle) of a board to use, and you can always use the cutoffs to make boxes, test pieces, featherboards, pen blanks, push sticks, or whatever.
I get the feeling that you must choose between more shorter boards or fewer longer boards, but that's what's confusing to me.
If you're deciding between 3x five foot boards or 2x six foot boards, I might choose the former to get more useable boards, but the exact choices are not clear to me.