I think Molly wants the cameras on her and is prepared to play up to get that. She is just setting up scenes all the time.
Challenging the new girl to a “plank off” would get air time, especially if they had actually done it, and she knows it. It is reminiscent of when Ekin-Su challenged Natalia to a pancake competition.
In the same way, when she was peering through the leaves to watch the date and stayed there, that was nicely set up for effect.
I’m not sure that she has a genuine interest in Zach or anyone else, but she is an aspiring actress who wants exposure so I think she will play any character to get that. Ekin-Su played her part up the whole time and has been very successful since leaving.