On the 777, I noticed that a lot of guys wind down the speed when there is light to moderate turbulence. They claim that by reducing the speed, the ride will be smoother
I don't think anyone has really addressed the original question or the "reasoning" behind it.
The only aircraft I've flown have a stated "turbulence penetration speed" published. This is a speed decided by the manufacturer that maximises buffet margins (high and low) in the event of extreme IAS excursions - in other words is specified for structural and control reasons. It surely has nothing whatsoever to do with comfort/ smooth ride.
I frequently fly with FOs who, as soon as a bump is felt, wind the speed back to turbulence speed "because we're in turbulence". My impression is they do this in the belief that it is required for pax comfort rather than being limited to structural limitations in extreme turbulence as opposed to light chop. This technique is so widespread I'd say it is almost universal in my company so there are clearly misunderstandings in the practical use of Turb speed.
"But we're required to use turbulence speed in turbulence" is the usual response - usually accompanied by a "everyone knows that, what the &%$£'s the matter with you?" look. (It is an airline noted for pavlovian training methods)