A pilot that owns the plane should have long since understood the operation of the fuel selector, and nothing but total carelessness and complacency should get it in the off position . And a new checkout, just emphasize “Don’t Turn It Off”. Situation solved as if after almost 60 years of using this fuel selector there actually is a situation. And yes, “select fullest tank just before landing” , not hardly. If my motor is running close to the ground, I won’t be touching it.