Yes, I think you're right. What irritates me is why are they waiting until after the print book has been released to release the official errata. And my guess there would be they decided to hold off the release until they had some certain amount of changes. I think it is poor optics having a change inaccessible in DDB when it is in print.
Based on Crawford's twitter feed, they try to time them to try to be simultaneous. But obviously it doesn't always work out perfectly. I think we'll see the errata document soon. When you look back at it, you'll think, 'Oh, those came out about the same time'. Or maybe you won't. I probably won't ever think about the timing again.
And I don't think they wait until they have enough changes necessarily. I think they wait until they think they've got them all for a given book. (Though obviously they fail, and I'm just guessing)
AD