The problem is that flying further apart means that larger relative velocities can build up before they're detectable. If you're not on the ball, you can end up scaring yourself much more easily. Bizarrely, I found (in close formation) it's easier being tighter than loose, where you can find yourself being whipped about on the end of the imaginary elastic string more. Of course, being more than a couple of hundred yards out isn't really 'formation' in the strictest sense...