When White House press secretary Sarah Huckabee Sanders holds an official press briefing, time is a precious commodity. May 22: “We’ll keep this short today.” May 17: “Sorry, I’m going to keep going because we’re really tight on time today.” May 7: “Sorry, I’m going to keep moving just because we’re going to get real tight on time here.” May 7 (again): “I’m going to just keep moving because I did it to your colleague.” For a more lively look at the press secretary’s time constraints, please click on the video at the top of this post.

It stands to reason that Sanders may well be watching the clock. Her briefings, after all, have a knack of ending at 20 minutes, or a tick before or after that mark. As The Post’s Philip Bump pointed out in an exhaustive quantitative look at White House press briefings, Sanders has averaged 20 minutes at the podium for her press briefings and gaggles (which tend to be shorter than full briefings). According to the calculations of the Erik Wemple Blog, Sanders’s briefings have clocked in at 22 minutes or less at least 28 times over the past six months.

It wasn’t always thus. According to George Condon, a National Journal White House correspondent, the senior wire reporter in the room has traditionally thanked the press secretary after an extensive Q-and-A session. Legendary UPI reporter Helen Thomas performed this function for years. “Before she would say, ‘Thank you,’ she was in the first row and she would glance around to see if there were hands still up because she didn’t want to cut it off before people had a chance to ask questions,” recalls Condon, who has been hanging around the briefing room since 1982.

Retired AP reporter Terence Hunt also executed the ritual. “I usually waited 45 minutes or an hour before ending it with a thank you. Occasionally I overlooked someone in the back when the briefing dragged on and when that happened, they gave me grief,” Hunt told the Erik Wemple Blog in an email.

Lengthy briefings continued through the end of the previous administration. “I mostly noticed it in the Obama era, particularly when Josh Earnest — to his credit — would try to take every question in the world,” says Olivier Knox, who covers the White House for SiriusXM and will assume the presidency of the White House Correspondents’ Association this summer. The “thank yous” no longer happen. “That’s completely dead,” says Condon.

Though Sanders softens her image with references to birthdays and other trivialities, cramming a legitimate-appearing press briefing into 20-odd minutes requires ruthlessness. There are 49 seats in the room, with various reporters crowding the sidelines, all equipped with questions. To leave the impression that she has sufficiently polled this crowd, Sanders moves quickly from journalist to journalist — and skimps on the answers.

Sample a string of exchanges from Sanders’s May 9 briefing. Asked about then-nominee for CIA director Gina Haspel’s declaration that she wouldn’t re-launch interrogation programs, Sanders said Trump had “confidence” in Haspel and would “allow” her to lead. Pressed on whether the president still believes that torture works, Sanders replied, “You know, honestly, I haven’t had a conversation with him about that recently.”

Next came a pair of questions about the president’s legal troubles. Doesn’t the American public deserve an answer to questions about a shell company controlled by attorney Michael Cohen? Sanders: “And I think there are appropriate venues and channels in which to do that. And I’ve encouraged you to reach out to them to do exactly what you just outlined.”

Moving on, the press secretary fielded this thoughtful question on foreign affairs:

On North Korea, before he was the National Security Advisor, John Bolton was critical of the Obama administration for sending Bill Clinton to negotiate the release of American detainees in 2009. Did the National Security Advisor raise any reservations at all about the current negotiations? And can you talk about what circumstances are different now than they were in 2009 to make it more appropriate?

Just how do you answer that one in 35 words? Sanders provides a tutorial:

I’m not aware of anything that he raised. Also, to be clear, the purpose of Secretary Pompeo’s trip was to negotiate and discuss the upcoming meeting between President Trump and the leader of North Korea.

Informational parsimony is the key here. Never surrender too much stuff; always highlight moments when you haven’t spoken with the president about a particular topic; shun complexity; and if there’s some other instrumentality, some other bureaucrat, some other spokesperson to whom a question can be referred, refer. “Smart brevity,” this is not.

Just what is the rush here? We asked Sanders that very question and didn’t get a response. Sometimes, however, she provides an explanation in the sessions themselves. On April 10, for instance, Sanders was in full hurry-up-offense mode. “Sorry, I’m going to keep moving because we’re tight on time,” she said at one point, only to repeat the imperative moments later: “Sorry, we’re tight on time with the visit of the Alabama team coming up soon.”

Was it a coincidence that Sanders was attempting to jam her briefing in just before the critical visit of the Crimson Tide? Priorities matter: Journalists were cut short on their questions so that all eyes could land on the president as he welcomed the national-championship football team, saying, “Great job. Big guys back there, huh?”

Like many phenomena in Trump world, the brief press briefings are both unacceptable and logical. Sean Spicer, Sanders’s predecessor, attempted on repeated occasions to tangle with the White House press corps on the nitty-gritty of the day’s news. His briefings, accordingly, lasted longer than those of Sanders, much to his detriment. Back in April 2017, for instance, Spicer fielded a question about the alliance between Vladimir Putin’s Russia and Bashar al-Assad’s Syria. He said, in part, “You look — we didn’t use chemical weapons in World War II. You had someone as despicable as Hitler who didn’t even sink to using chemical weapons. So you have to, if you’re Russia, ask yourself is this a country that you and a regime that you want to align yourself with? You have previously signed on to international agreements rightfully acknowledging that the use of chemical weapons should be out of bounds by every country. To not stand up to not only Assad, but your own word, should be troubling.”

About three months later, Spicer announced his resignation, leaving behind a paradoxical lesson for his successors: The less time you spend defending this president, the longer you’ll last.