OK, if responses are down, just ask for some advice.
I got LOTS of responses, which as you'd expect, fell pretty cleanly into two camps. Those reading the story all wanted it to continue as is, while those not reading the revision wanted to see 'new material'. However, what they all seemed to agree with was 'Don't Post all at once', as that will make readers assume I'm abandoning the story! I also got several requests to slow the postings down (that's discussed below).
However, some other details popped up which sort of answered the question for me. My downloads, responses and ebook sales have all dropped since I switched to post three chapters a week. When I saw that, I remembered I saw a similar drop when I switched to twice a week.
It was especially noticeable when I posted chapter 12. It's got a cliffhanger ending (something I don't do very often). Normally when I post these, there's a spike in comments and additional ebook sales, as people are anxious to either discuss it, or see what happens next. This time, the responses were both delayed and ... muted. It seems that people want to talk about it right away, but if there's another chapter coming in only a couple of days, they figure 'eh, what the heck!'.
What's more, the posts to ASSTR seemed to cause a lot of confusion. Maybe I didn't announce it properly, but the chapter downloads were all over the place. Readers either didn't know when to check for new chapters, or simply felt overwhelmed and chose not to download certain chapters.
Finally, there are the workload issues. Posting twice a week makes it difficult to review each chapter before posting. And I traditionally make a significant number of fixes each time I do. This will be especially important as I get to chapters in the later books which I haven't revised. But at three chapters a week, I can't even glance at the latest chapters!
Thus I've decided to roll back my more aggressive posting schedule. Ideally, I think once a week postings are probably best for provoking feedback, generating interest and producing sales (as few as they are). However, there are just too many chapters to process, so I'll stick with the twice a week schedule.
As always, if you've got an opinion on this, or any other topic, let me know. I love feedback, as it provides useful insights and helps improve the stories!