Va and turbulent air penetration speed.

Kershner's "The Advanced Pilot's Flight Manual" has the following
definition for Va.

Va - The maneuvering speed. This is the maxiumu speed at a particular
weight at which the controls may be fully deflected without
overstressing the airplane.

Now, Va is commonly taught as turbulent air penetration speed. But
nowhere in the definition does it say that Va will protect the
airframe from damage due to turbulence.

Does slowing down even slower than Va protect the airframe from even
more severe turbulence? Or is Va the best speed for turbulence
penetration? Or is Va just used as a turbulence air penetration speed
becauase of tradition or some other non-technically correct reason.