I've written about the music composing process for weekly television dramas here before but I don't have time to go searching for it, but usually, if you've got a showrunner who is hands-on with the music of the series, he or she will invariably direct what gets used and what an individual episode's overall "sound" will be.
From previous conversations I've had with Jay Chattaway back when Voyager and Enterprise were still airing, I seem to recall him saying Peter Lauritson was the hands on guy with the music 99 percent of the time. He would be the executive producer at the majority of the sessions that would be calling the shots. The others (Berman and others) would only come by for the "bigger" episodes.