No, that isn't the point. The point is, if you actually practice reaching your tanks incase you forget to turn them on, then you seriously need a retraining. Surely instead of practicing reaching you should concentrate on making sure you were trained to turn your air on & check all your kit works before you even get near the water let alone in it. Your talking about jumping head long into a killer environment without making sure your only means of surviving in that environment is working. Now call me old fashioned but that seems just a little stupid to me. I have never needed to reach my valves & never intend to. My twinset is different & if you can't reach these then you shouldn't be using them (manifolded). Prevention's better than cure, especially when your life may depend on it.
Good (safe) diving
Rob