A number of years ago (late Smith/early Capaldi era, so 2012-ish to 2014-ish), I had occasional interactions with BBC Worldwide and BBC America. An issue that came up was how their hands were tied when it came to marketing because of the BBC's fanatical secrecy about broadcast dates. Paraphrasing some of these conversations: "They don't understand how television marketing works in the US. You start out months in advance. You plaster the launch date all over the place. And we can't do that." It was a source of frustration, especially since they were putting money into it, which is why they went heavy into putting the marketing into thing they could have some control over, like the Fathom movie events and SDCC.
My hope with Bad Wolf's involvement in the post-Chibnall era that the marketing gets more of a clue.