I've been flying RC heli's for over 10 years, and found that for precise control, I've developed the habit of pinching the sticks instead of just flying with thumbs... I realised a long time ago that I tend to "over control" i.e. go over where I want the stick to be when I'm just using thumbs... Even though the Mavic controller is a bit cramp for pinching, I've managed to get used to pinching the sticks with thumb and forefinger with the third fingers resting on the wheels for gimbal/exposure control. I haven't found the need to use the C1/C2 buttons so it hasn't been an issue with my hand position on the controls.
That said, a lanyard to help with holding the weight of the controller is essential.
That said, a lanyard to help with holding the weight of the controller is essential.