With a well tuned arrow tipped with a field point, you should be able to accurately shoot 20-30 yards with no fletching at all. You would be more accurate with 2-3" straight fletchings, because we don't live in a perfect world.
The same 2-3" straight fletchings would not adequately control an arrow tipped with a broadhead, no matter how well your arrow is tuned. You would get the best performance out of your bow if you shoot the least intrusive fletching that would do the job. So you would make up a series of arrows starting with 3 - 4" straight fletchings, and ending with 4 - 5 1/2" helical fletchings, shoot them all many times, and pick the one that gives you the control you need with the smallest and least curved fletchings. This would be tedious.
Or, you could just pick 3 - 5" helical fletchings, a combination that has proven effective for many people, and live with the fact that you might be leaving some speed on the table.