Usually, the sets are mostly in terms of importance. However, as the disclaimer in most analyses says, the analyses on the website are outdated and are being reworked, so there's a good chance that the sets that were "finished" got uploaded in rapid succession and left as is without too much thought until the metagame settles down a lil' bit; you can see that this is true in almost every single old gen and lower tier where things tend to be more stable once they freeze from a generation passing (don't look at SS OU analyses- they just aren't there!).