@Chrchill - What I’ve noticed is that the interviewees tend to start their pithy recitation of some such with "So . . . ". This is true whether the person be a reporter, a scientist, a commentator, or whoever. It’s very interesting that they all seem to have this habit (tic?). The “So” introduction is invariably followed by a set of facts with a little bit of commentary thrown in for good measure, making the speaker sound informed and intelligent (at least to NPR listeners). It’s some sort of NPR-speak.
Very different from using “So” at the end of a sentence as in “I don’t listen to NPR, so . . . " which is a tad dismissive and makes the listener immediately think So . . . What?” That use of “So” substitutes for a coherent ending to the statement,
Neither should be used in writing. So! (or as I like to say: So Now!)