That's exactly the point. Those "short" challenges are pointless, as the factor "luck" simply has to much of influence to a fair competition. Another point is the schedule your team finds yourself in during that short challenge. If you're lucky, you're playing some **** the bed teams, but if you're not, you've to play 2 or 3 of the best league defenses apart of your own.
So, if any challenges, than make those fair for all competitors, eliminating the factor luck to a bare minimum, or even better, just avoid such nonsense entirely...