That is the classic pose for shooting a gun off a bench with a rest while seated.
Notice a couple of things, the rest supports the fore end of the gun, not the barrel. To increase accuracy the barrel has to oscillate the same way every time. Putting the barrel directly on the rest will change the harmonics of the gun as the bullet leaves the barrel.
Notice too that the free hand is NOT supporting the fore end. Let the rests do its job! You can put the NON shooting hand as a support to the elbow of the shooting hand.
Sand bags make an excellent rest for shooting, but multi-purpose rifle rests also work well. Small sand bags for a rear butt-stock rest also help A LOT! I use Sandbags most of the time, and find I have better luck.
When using a shooting bench, stability is your goal. A wooden bench is fine, but a concrete bench is even better. Make sure the wheels lock, or at least chock them in place with a chunk of wood or something.