Maybe the posing and the invisible phone thing are nerves.
She doesn't seem very confident to me really, despite her career (past and present).
She's been quoted as saying she feels embarrassed to smile in photographs as she doesn't like how she looks, and to me that sounds insecure rather than arrogant.
Lots of people put their hand over their mouth in photo's, or hide behind their hair, or smile in a way that doesn't show their teeth, or turn to one side rather than the other. Or just flat out refuse to be photographed at all.
She can't do that. Her own career, her relationship, her friendships, her children, everything about her means she's going to be in the public eye, and that means she's going to be photographed whether she likes it or not.
And if she's practicing poses for hours so she looks right in them, that to me says that she feels very insecure in how she will appear and is trying to make sure in her own mind that she looks good.
Maybe some people do that out of arrogance or whatever, but looking at those two photo's above, she doesn't look like she's thinking "I look great" to me, she looks more worried than that, more vulnerable. T
The one with David, he looks happy and secure in himself, she looks like she wishes she wasn't there at all.