Re: flow, or technique
Saotome Sensei, I think in one of his books--and if not, it's in one of Gleason Sensei's books quoting him--says that for shodan he's looking for precision of technique. All the parts in exactly the right place at the right time. For nidan, he's looking for fluidity, to see that all the parts have been integrated into a whole movement. Sounds like a similar sort of progression.