Part of it is FOX trying to put "their brand" on their coverage, and I think another part is that they're convinced the average viewer wants a lot of jump cuts, and that viewers will change channels without it. That's why they have headlines running across the bottom of the screen, stock prices, time and temperature, upcoming stories, etc, circling the talking heads during broadcasts.
Whatever happened to, "We Report, You Decide"?
I was disgusted with the Fox coverage of the plasma press conference on Sunday. While the big news was being announced, Fox's chyron ran a continuous stream of how Mary Trump thought Donald Trump had "no principles".