Setting aside the question of how useful it would be for Trump to sit in on meetings about oil prices in Pakistan, or some such thing, there is a very plausible and reasonable explanation for him taking good quantities of executive time. One of the curiosities of the Trump presidency is that he is basically his own communications director. No president since Richard Nixon has taken such a hands-on approach to his White House’s messaging, and Trump probably even has Tricky Dick beat.
Anyone who works in comms — or some kinds of journalism, for that matter — understands how forcefully cable news shapes narrative, and how Twitter affects how that narrative develops. No politician has ever dominated the media narrative as effectively as Trump has. He is the news all day, every day. Part of how and why he established this dominance is by immersing himself in these platforms.
Trump isn’t just “watching” cable news, and he isn’t just “surfing” Twitter. He’s researching and influencing. He is seeing what attacks of his are landing, and what attacks against himself he can expect.