The biggest weapon in GOT has always been information, with how and when it's been used. Let's not act that Varys didn't have his Little Birds or Littlefinger didn't have his whores to give them information, that they used over people to achieve goals. So it's all in the game if Sansa getting info from Bran. Sansa lived with Cersei, she knows exactly what kind of person Cersei is and the bile she has for the North she didn't need Bran to tell her that.
Samwell is book smart, that's far different to being able to read people and maneuver around politically, especially with already established relationships, which is about playing on a person's ego/fears/weaknesses.
Let's not forget Sansa at the start of this journey wanted to be a down south Queen, knocking out royal children and couldn't wait to be free of the Starks and only thinking about herself, she's done a complete 180.
that's it, I don't know why people are acting like this doesn't apply to Sansa. Also as you have alluded to she's been around and seen shyt.