In 1950 when being trained on the Link D2 it was possible to have the whole operation either with or without " Rough Air". ( Whether this could have different settings - has been forgotten.) We started with "Calm Air" and learned to fly on instruments and stalling and how to recover from a spin. Then "Rough Air" was used for most or all of my training. As a new pilot I felt that it was unlikely that I would spend the rest of my instrument flying time just under calm conditions. ( I was right !)
Thanks to the random nature of the "Rough Air" one learned to maintain ones flight path with greater accuracy. ( "Calm Air" was easier - but not as useful as a lesson.) Later, hand flying alternate hours with the Captain, when it was " my hour" to hand fly a York, sometimes we flew into an unseen/ unsuspected Cb. The randomness of the Link meant that surprise or shock of sudden turbulence even when accompanied by lightening strikes, St. Elmos Fire and squeals of static were just additional effects.
(165 Kts. IAS or about 180 kts. TAS and just below 10,000ft. I assume that a higher TAS would have meant that we would hit each cell harder.)
( Radar was not fitted for a further ten years, for me. Then it had become a "No Go Item". And I could radar map read - at night, too!)
LT