I've always thought that it was a mistake to start the third film rescuing Han.
If it was that urgent we would have skipped the bit where Luke's hand heals and had the whole gang leave the fleet with Lando and Chewie.
So for me Luke has spent the gap completing his training (in the absence of a fan-edit he did this telepathically with both Ben and Yoda but with increasingly powerful interruptions from Vader psychically trolling him).
After saving Han with a plan that currently makes no sense at all he goes back to Jedi camp where Yoda can die in confidence knowing that doesn't really make much difference as he can phone in anything else from Jedi Valhalla.
So he has two teachers with conflicting attitudes.
Ben (Fibby-Wan) Kenobi : is more militant. He urges Luke to face the enemy and destroy it.
Yoda is more Taoist. He sees Vader and the fear of becoming Vader as Luke's weakness. He must face his fear for real (in the way he failed in the cave) only then will he receive the secret insight to save the day.
FFWD to DEATH STAR 2 :Electric Boogaloo.
Luke has just gone boingyoingyoing and has a blade at his Father's neck. He has defeated his Father but stands on the edge of becoming Vader or worse.
Palpatine makes the over confident error of gloating about this which wakes Luke up to what has happened. He still has a choice.
He says NOooooooooooooooooOOOOooooooooooooooo! (only in a more dignified way than is usual for this series).
This is the end of Luke's importance to the story. His compassion and Palpatine's dickishness is a wake up call for Anakin. If Luke is willing to throw his potentially long and successful career as the boss of all things away to save his dad from the man, he (being an old barely alive torso in a robosuit) can throw what left of his life (and his backstabby old git of a boss) down an inexplicably placed hole in the floor to save his not so only child.
Luke doesn't really have a plan beyond hoping to save his dad before the station explodes. He totally fell for the boss queen of the galaxy sitting in the unfinished, not operational, barely protected, planet smashing death ray machine schtick.
The plans are made for him by old men, Ben, Yoda, Vader and Palpatine. He might has well have stayed on the farm and let Owen boss him about.
Luke's essential power comes from rejecting the advice of older people and being his own man.
UP YOU...OLD GUYS!