Some drivers use this technique before/while doing a turn. This could be quite terrible in the event of a collision where the steering wheel airbag were to deploy – which does so at about 300 km/hr. Arms could also potentially get stuck and injured in the event of a collision.
To turn a corner, signal well before the turn. When the way is clear, move into the proper lane, either the far right lane for a right turn or the far left lane in your direction for a left turn. Signal your turn and look from side to side and check your blind spots to make sure the way is clear.
Slow down before you enter the turn; the sharper the turn, the slower you should go. To keep full control of the vehicle, finish braking before you turn the steering wheel.