Luke Skywalker never learned from the Jedi's greatest mistake in the Star Wars saga. Yoda had trained Jedi for 800 years, and it is fitting that his last request was that Luke Skywalker - his final student - should pass on what he had learned to the next generation of Jedi. It was also rather odd, given Luke had only spent a brief period of time under Yoda's tutelage, and the Jedi Grand Master had barely managed to get past basic lessons. Fortunately, Star Wars comics have revealed Luke did indeed learn from other sources after leaving Yoda's side on Dagobah; he even discovered an ancient Jedi text, recovered from a Force vergence called the Living Sea of Gazian.
Luke didn't immediately found a new Jedi Order, instead spending the next five years of his life wandering the galaxy, seeking other lost records of the Jedi. He discovered temples from the High Republic Era, Holocrons in which Jedi Masters of the past had recorded their teachings, and even an entire treasure trove of Jedi knowledge secreted away by prequel era archivist Jocasta Nu before she was killed by Darth Vader. Luke managed to piece together much of the recent past, coming to understand how Palpatine had destroyed the Jedi through the Clone Wars. Unfortunately, the sad truth is that he failed to recognize their greatest mistake.
Palpatine Took Advantage Of The Jedi's Greatest Weakness
Centuries ago, the Jedi had maintained countless temples across the galaxy, and had lived among the general population. All that had changed by the time of the prequels, however, with the order centered at the Jedi Temple of Coruscant. The Jedi became distant and remote, caught up first in the affairs of the Senate and later in the Clone Wars. They never interacted with the citizens of the galaxy, and civilians seldom even saw a Jedi from a distance. This remoteness meant the Jedi did not understand how ordinary people lived, and the people did not not understand the Jedi. The Jedi philosophy of avoiding attachments meant Jedi struggled to relate to those who had not grown up in the order, while others thought them cold and aloof.
Palpatine, of course, took full advantage of this. As a prominent politician, he was able to appeal to the public in a way the Jedi were not; by the time of Star Wars: Episode II - Attack of the Clones, Palpatine was undermining the Jedi by suggesting they were too limited to fulfill their traditional role as guardians of the Republic. The in-universe book Star Wars Propaganda: A History of Persuasive Art in the Galaxy shows a poster used by Palpatine to encourage people to believe justice needed more than lightsabers. During the Clone Wars themselves, Palpatine ensured people saw the Grand Army of the Republic as their champions - not the Jedi. In the end, he was able to turn the lack of connection between the Jedi and the wider galaxy to his advantage, telling a lie about an attempted Jedi coup.
Luke Skywalker Repeated The Prequel Jedi Mistake
It is, sadly, a matter of record that Luke Skywalker repeated this mistake. Luke established his Jedi Temple on Ossus, a vergence strong in the Force, one where his students could train without interacting with others. Presumably he did so in case any more spectacular lessons went wrong, potentially causing problems. But Ossus is a surprising choice for the Jedi, because it is one of the most remote planets in the galaxy. It was almost inaccessible, with twisted hyperlanes that were almost impossible to navigate. Luke created a Jedi Order that was even more distant from the galaxy - and he paid for it. When Palpatine ultimately had Luke's Jedi Temple destroyed, there were no emergency services on hand to comb through the rubble. The hero of Star Wars had passed on what he had learned - but his students had then been wiped out.