I'm not so sure how Bran decides to know something and not know something. For example, when Littlefinger presented the dagger to Bran, Bran said "chaos is a ladder" which is a line LF used years ago. When Bran was reunited with Sansa he talked about her wedding to Ramsay as if he had been there. Does Bran just decide to 'download' a person's life when he meets them? If so, then when Sam walked in Bran should've already known about the secret wedding before Sam told him. Bran 'divining' that info from Sam would've been much more in character than Sam having to tell it to him.
On a more strategic note, why aren't they using Bran's powers to constantly spy on their enemies? Other than because it's bad for the plot of the show, there's no reason Jon, Daenerys, Sansa, etc., shouldn't already know about Cersei's plan to break the pact, Euron sailing to pick up the mercenary army, Jamie (presumably) ridding north alone, where Yara is being held, etc.,. Heck, just have Bran take control of some animals in order to kill Cersei and Euron and be done with it.
Earlier in the season when Bran talked about himself as the Three-eyed Raven I thought he wasn't going to consider himself a Stark anymore (and maybe not even a man) as he had ascended to a higher plane and no longer concerned himself with these 'trivial' problems of mankind (similar to the position Doctor Manhattan takes in Watchmen). But when Bran sat next to Sansa and provided the key evidence to prove LF's guilt then I was like, "Okay, I guess Bran is going to remain active member of the Stark family." Which goes back to my point that Bran should be constantly spying on (and probably assassinating) their enemies at every possible turn.