If it's Friday, there's a good chance for a major personnel reshuffle in the Trump White House. It was on a Friday last month that Sean Spicer's exit was announced. It was the following Friday that chief of staff Reince Priebus was pushed out of office. And on this Friday it is Trump's chief strategist Steve Bannon who is forced out.

But while all three exits involved senior White House operators and occurred on a Friday, there is at least one major difference between the ousters of Spicer, Priebus and Bannon. Unlike those now-former colleagues, Bannon should never have been in the White House to begin with.

To be clear, both Spicer and Priebus - for different reasons - were disasters in their respective roles as Trump's spokesman and chief of staff. But one could at least make a case for both in the president's inner circle, as they had been leading figures with similar portfolios in the Republican Party. Moreover, they served, for better or worse, as an important institutional bridge between the Trump White House and the GOP.

Read more: Four facts about the former 'Darth Vader' of the White House

Nationalist in the White House

Bannon, in contrast, was not. Not only does he lack a close connection to the Republican Party, but in the past he has repeatedly voiced his disdain for it and its establishment – a sentiment that connects him with Donald Trump. But even more, and much worse than that, Steve Bannon can be seen as a link from the White House to the so-called alt-right movement, which played a leading role in the violent march by the extreme right last weekend in Charlottesville that left one person dead.

Bannon, who headed the conservative website Breitbart before managing Donald Trump's then-stumbling presidential campaign, not only said that he had turned Breitbart into a platform for the alt-right, but in an interview also proudly described himself as a nationalist. During the campaign and since becoming Trump's chief strategic adviser, Bannon has arguably steered the president toward an anti-immigrant, anti-Muslim and anti-trade agenda.

Trump's ill-fated travel ban, his administration's hard-line stance against undocumented immigrants and Trump's trade policy bear Bannon's mark. How much of this was really shaped or conjured up by Bannon and his allies in the White House is hard to tell, but at the very least Bannon was a negative amplifier of Trump's own negative impulses. At the worst he was a vicious demagogue and rabble-rouser who elevated nationalism and xenophobia to the White House.

Ruthless operator

But Bannon was not only a nationalist ideologue; he was also a ruthless infighter in the constantly feuding Trump White House. Bannon was bent on advancing his agenda and hired former Breitbart staffers to help him along. More than that, he also tried to push out people he saw as opposing his views. On Wednesday, Bannon, in a puzzling interview with a progressive magazine not only openly contradicted President Trump's North Korea policy but also boasted that he was getting rid of Susan Thornton, a top State Department official.

Whether the interview hastened Bannon's exit is difficult to say, as there appear to be different versions of what happened - a frequent occurrence in the Trump administration. But since speculation about an impending ouster of Bannon had been circulating for weeks already and gained traction since John Kelly became White House chief of staff, the interview may have been the straw that broke the camel's back.

"Deconstructing the state"

While Bannon's exit is good news as it severs an inside line alt-right supporters and nationalists had to the White House, it does not mean his ideological fervor will be gone. In fact, there is a good case to be made that Bannon, freed from any official shackles, can advance his nationalist agenda even more effectively from the outside via Breitbart and other channels.

Read more: Opinion - Trump is following Bannon's agenda

Trump, having elevated Bannon, who once said "dark is good," to global prominence by promoting him to a senior White House role in the first place, could find it impossible to put the genie back in the bottle after he is gone. That's because Bannon could easily opt to turn up the heat against Trump and his administration should he decide they were straying too far from his nationalist agenda, which in turn could threaten Trump's connection with one of his core constituencies.

In any case, Bannon, who after taking office proclaimed the "deconstruction of the administrative state" as his goal, can proudly tell his many fans and followers that he made good progress toward that aim in his half-year in the Trump White House.