Ah, subtly different question.
The C206 is I believe a part 23 aeroplane, in which case a gust analysis would have been done as part of the flight envelope determination. This should have led to determination of a maximum speed for flight in rough air.
This should be in the POH somewhere and designated either VB or VRA . So long as you are staying below that in moderate or worse turbulence, I don't think you've anything to worry about.
I've never worked on any of Cessna's products (flying a Cessna single occasionally is bad enough) but I'd guess the progressive reduction in Va is down to certification office concern about turbulence causing g-loadings to detach ancilliary items like batteries, crew and so-on - which is fair enough, but wouldn't jeapordise the whole aircraft.
Also, do you have a g-meter? If you have, and are not seeing anything worse than about 3g in those descents (limit is 3.8 I believe, but pitch rates can increase the value at extremes of the aircraft) then my uninformed instinct is that you're probably okay.
G