You can't keep a stretch on your left arm if your right arm bends past 90 degrees. Plus I'd think that the chances of ending up in a 'doublecocked' wrist condition - both the left AND right wrist being cocked - would also be a danger.
matt i have been fighting a doublecocked wrist conditin for 20 years- this might be one of my causes. i need a drill to keep it at 90*. anybody have any suggestions?