I am about 25% of the way through my first draft, making cuts, edits, and revisions. So far I haven't felt like I had to strip anything major out and rewrite it, but I haven't come to the really Big Events yet.
I've come to realize that I probably obsess more about plot holes than most readers do. Considering the plot holes that Rowling was forgiven, I don't know why I hold myself to a higher standard, but I do. Sometimes the things I think are plot holes probably aren't, and sometimes it might be only me who notices them. But I simply cannot leave a plot hole unfixed.
I know my storytelling and my worldbuilding isn't airtight -- people have pointed out small details here and there that aren't quite right or consistent -- but I don't think I've dropped any major bombs in the first three books.
Rowling, in my opinion, was guilty of her first major plot hole in book four, which is most concisely expressed in How GOF Should Have Ended.
Before that, there were plenty of things you could nitpick, but I have yet to hear a non-stupid explanation for why Voldemort and Moody had to go to the ridiculous lengths they did in GoF to put a Portkey in Harry's hands.
And yet, readers (including me) are willing to forgive her for that. So probably if I screw the pooch in a major way, plot-wise, readers will forgive me. (Right? Right?) But I don't want to do it, hence my trying to think of alternatives and a countermeasure to every scheme, like a criminal trying to out-think the cops who will be looking for any mistakes he makes. What I especially don't want is the sudden realization: "Oh wait, Abraham Thorn used a spell in book two that makes this entire chapter pointless!"
I probably will not succeed in writing a bulletproof seven-book series, but although I spend an awful lot of time deliberating over which verb tense to use and whether a clause is necessary and commas or em-dashes (seriously, there isn't a single sentence I can't go back and decide could be rewritten better), it's really plot holes and internal consistency that preoccupy me.
Okay, but I do rewrite almost every single sentence too. So I guess that also preoccupies me.
So I just finished rewriting chapter twelve.
The number of chapters is still mutable; I've already split and combined chapters a couple of times, and I have a couple of 9000+ word chapters that are candidates for splitting, too.
Also, if you are considering making it to the DC area for CapClave, there are four of us so far who are "maybes" to "almost certainly"s (I have no idea what kind of gathering we will have if there is a mini-gathering of AQ fans; probably we'll all just go out for dinner or coffee or something), so email me if you are interested.