The Accleration of Political Rhetoric

From Confidence Men, by Ron Susskind, pg 23-24:

But it was hard to know how even Lincoln’s rhetorical genius would have met the awesome challenge of modern politics: to explain hugely complex problems and offer first-step solutions in all of sixty seconds. Hillary Clinton could do it just like Lincoln split wood: steady and true, swing by swing, as the clock ticked—fifty-four seconds… fifty-five… fifty-six—her final summarizing sentence would hit its period and leave her three seconds to step back and consider what she had said, as though it had all just dawned on her. Obama watched her, on stage after stage, suppressing his amazement. He found the demands confounding and unreasonable, and he responded with a professorial mien, oddly uncertain, offering what felt like introductions to dissertations never to be completed.

How much of the professional socialisation of contemporary politicians represents a direct or indirect response to this challenge? A whole apparatus serves ultimately to facilitate strategic communication under such constrained circumstances. 

In contrast Donald Trump rambles when speaking at length and accelerates when denied time to ramble. How does this help prop up the sense of the authenticity of his speech?