Lord Haseo said:
Luke’s training was arguably the best part of ESB.No.
I didn’t say it was definitively the best part but I can see how someone can think so. There is oodles of character development even before Yoda accepts his training. From Luke being frustrated at the X-Wing crashing to swamp to him being impatient to get to Yoda…all of that develops his character. And when the training starts we learn more about Luke, the Dark Side and the Light and life itself. It doesn’t matter that Luke’s training was mostly just working out and lifting stones because those scenes lead to character growth that cemented his transformation from a whiny farm boy to a serene, confident and mature Jedi Knight. Lastly, his fundamental struggles occur during this time as well which also adds to his character arc in the OT.
As for the placement of the training being mostly in the 1st act it won’t matter because there can be exciting moments in there as well. Rey sparring with Luke, Kylo sparring with is Knights and in Kylo’s case he should have a final test before he is anointed by Snoke as someone worthy of continuing the Dark Side’s imperative. Sprinkle in an action scene with the Resistance and the set up for their story line and you have a really good 1st act and then you have the rest of film be more focused on the story lines instead of the training.