Benchrest has its place, as does offhand. Sight in for benchrest, but shoot offhand when getting ready to take to the field. Cooper's book The Art of the Rifle is an excellant source for learning from (if you can't get a coach or instructor).
I practice it, but with a .22 at clay pigeons (stationary) at 25 yards. The only other time I regularly shoot offhand is at Running Deer or blackpowder.