I have been told to keep the left wrist straight when doing chromatic scale and move only fingers.
the problem happen with the 6th string , I try to keep to wrist still and let the finger curve to reach the note, but I notice that with ring and pinky finger can reach but it has less space and can easily mute the 5th string ( I mean they doesnt curve nicely and I have to cup my wrist a little to have more strength and room for those fingers.
Another cup wrist occur when concern with barre chord such as barre on 7 fret and pinky on the 1st string 12th fret. and other 2 fingers have to work for melody part as well. I have to cup the wrist ( bring it forward ) to have more strength. I feel like I have to use the muscle at the back of the palm to help with the passage.
need to practice more!