how much time elapsed between new hope and return? I feel like they could have been on hoth for awhile. Yeah they barely had the fighters setup for cold but with the base and finding hoth and such it could be years. Then between empire and return you have a whole bunch of offscreen stuff. Luke makes his own saber and seems to have done some sort of self training given how good he got (maybe more with yoda but it did not sound like that when he speaks with him). It was implied lando had to find where han was taken and stake it out and the whole plan had to be figured out and implemented and they knew he was safe sitting as a decoration. I mean that could be over a year or years as well.