President Trump continues to muse about the possibility of replacing White House Chief of Staff John F. Kelly with . . . no one. And that should worry all of us, if for no other reason than why he thinks he could do it.

“A Republican in frequent touch with the White House said one of the clear manifestations of Trump’s newfound unilateralism can be seen in the comments he’s made to aides and confidants,” my colleague Ashley Parker reported on Monday. “When his current chief of staff, John F. Kelly, departs the White House, Trump has told them, he may prefer the model of President Lyndon B. Johnson, who did not name an official chief of staff.”

It is no secret that Kelly is miserable trying to be the responsible adult in a White House that runs according to presidential impulse, and that he has his eye on the exit. Nor could it help that his boss views the chief of staff’s job as entirely dispensable.

But Trump, to put it mildly, is no LBJ.

Johnson came to the job unexpectedly — with the assassination of President John F. Kennedy — but not without preparation. “He had a vast store of knowledge. He’d been in Washington 30-plus years. On any legislation, he knew the substance of it,” says Joseph A. Califano Jr., who was Johnson’s domestic policy chief. Johnson also had long relationships with all the key political players in Washington and beyond.

Perhaps even more importantly, and differing greatly from the hurly-burly of the Trump White House, Johnson and everyone around him had a clear, fixed idea of precisely what he wanted to get accomplished. As Califano put it: “Everyone on the staff knew what the priorities were.”

So how did Johnson manage without a chief of staff?

While no one held the title — which had originated with President Dwight D. Eisenhower, as a carryover from his military days — Johnson always had a designated aide who handled the flow of information into the Oval Office. For much of his presidency, that duty fell to special assistant W. Marvin Watson. Califano recalled that Johnson would leave the office each evening with a stack of what was called his “night reading” — memos of no more than two or three pages submitted by his top aides, which the president would consume while either getting a massage or lying in bed. He was to check one of three boxes on each: “approve,” “disapprove,” or “see me.”

“Anything I sent him, I got an answer the next morning. It was amazing,” Califano said.

It is hard to imagine that kind of system working for Trump. For one thing, it would cut into his nightly cable news watching. For another, he does not like to read — preferring, for instance, that his daily intelligence briefing be delivered orally.

But Trump should also take pause from the fact that LBJ’s decision-making was far from perfect. Johnson’s presidency will be remembered as much, if not more, for the tragedy of Vietnam as for its domestic legislative achievements. There, his faith in his knowledge and his instincts failed him.

“In Washington, he knew every card in the deck, but in the world, he didn’t,” James Reston of the New York Times wrote, “He knew very little about Vietnam. He was not very comfortable with what he called the “fancy-pants” characters in the State Department and the Foreign Service, who knew a great deal more than he did about the philosophy and escape-hatch boundaries for guerrilla warfare in Indochina, but he had a strong personal conviction.”

Does that sound familiar? Johnson’s is indeed a leadership model that Trump should study — because it holds a lesson on where a go-it-alone leader may end up taking the country.