i have straps on all my boards as loose as they can be
I loosened my surfboard straps and it felt good. However last week I had a high speed stacko and my back foot when right through the strap and ankle was on the wrong side too! I spent a very unpleasant 15 minutes drifting around in strong winds trying to get my leg, ankle and foot back through the strap. I couldnt loosen it off anymore with one hand.
If it had been impossible I would have had to dump the kite and protect my ankle from damage. A bit scary.
So my suggestion is if you do loosen off to the point where your foot could get jammed through, make sure they are loose enough to pull your foot back through the strap!