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I never saw a conductor twist.
They prefer the watusi! [Linked Image]

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To my mind the brass screw in threaded U style rose junction box that we have in the UK don't favour twisting;
Good point, the terminals on most modern ceiling roses are pretty small, but then they provide enough terminal positions for one conductor per hole in most situations. You only have to double-up if you want to parallel a second light, run a second thru-feed, etc.

I think there's also quite a difference between terminal styles on other fittings which can affect this. Compare the types where the screw clamp down on a small plate versus those where the end of the screw just goes directly onto the conductors.