As long as Jodi was testifying, it was beginning to make her seem like a weak little whipped puppy that MAYBE, just maybe was imperfect enough to believe Travis was the one playing with her emotions enough to cause the snap.
Having Samuels on the stand changed that back to proving the manipulative, conniving Jodi who would scheme, lie and do whtever it takes to achieve her own ends.
I know this is not a popular opinion about Jodi, but by the end of her time on the stand, she was SEEMING to be bullied herself. I don't believe she was. Being on the outside like this, I have the opportunity to see/hear things the jury is not privy to. They are not seeing the tapes of her psycho behavior during the police interrogation. Nor are they hearing the stories from people who actually dealt with her during the time Travis was trying in a gentlemanly way to get rid of her.
The only thing the jury can consider in deliberations is what they are presented in evidence in court. They cannot google, conduct their own experiments or watch the TH shows we see.
Dr. Samuels has admitted she lied and schemed to manipulate his professional opinion. I have the utmost confidence JM will leave the jury with the same conclusions I have.