YIKES!
The ONLY time I can think of where it's a good idea to let go of the steering wheel is just a moment before your car is about to hit a wall or something hard!
I once went to a school that said the same thing. All I can say is "It doesn't work for me".
When you release the steering wheel the steering will re-center due to the caster in the front suspension. The great the caster, the more quickly it will re-center. That means your wheels will be pointing straight ahead. Having them point straight ahead may or may NOT be the best position for the circumstances.
I'm guessing others will chime in... so I'll stop here.
Kiyoshi