@@NobuNobuSimp not true. I recently competed in dorney for junior sculling regatta and people who I know competing in national sculling regatta are also having now steered quads. So it all depends on the club/coach or the people in the boat and their preferences
The rule is you only use rudder or steer when the blades are in the water because it won’t upset the balance in that part of the stroke cycle. Never use the rudder during the recovery or when the blades are out of the water otherwise the boat tips and make the recovery and next stroke far from optimal slowing the boat and giving the opposition advantages