For me, it's not instant gratification, it's just writing/filmmaking 101 - if you can remove a scene and it has no impact on the story, then it doesn't need to be there - and it definitely feels like some of the Cassian/rebels scenes could be trimmed, deleted, or re-worked to include material that doesn't feel like it's going over the same ground.
Having watched the first 3 episodes again, although slow, it doesn't feel like they are saying the same thing, different ways - as the Cassian, ep 4 stuff did.
But at the end of the day, I'm SO RELIEVED to see something in the SW universe handled with such respect, care, and maturity.
(...and the production design and costumes of the Imperials and Mothma scenes has been exquisite).