What has hugely surprised me is that I can go back to a book, many times, and find new things in it. The key seems to be giving enough space between drafts. Not necessarily a lot of time, but a diversion, like working on the kids' book, or poetry, or developing books 2 and 3. Although it's hard to focus enough to work, at the moment, getting a gazillion edits back from people has really helped, so much that I sat down and worked non-stop yesterday on the MS, not only correcting silly mistakes, but seeing a few bigger ones as well.
In the past, I wrote one book, editing as I went, and was always disappointed at the end. I had invested massive amounts of time and energy, and it looked nothing like a finished book. I might even want to change several characters around, change the tone of the book. I've finally realised that the writing of the second draft is much easier and quicker than the first, the third is easier still, and by the seventh (I would never have believed I would read my own book 7 times, let alone write/edit it 7 times) I'm able to work through the entire book in a single day and produce a better, more polished version than the one that I thought was finished three weeks ago.
As Michael Crichton said (he wasn't the first): 'Books are not written--they're rewritten'. And rewritten, and edited, and written again. A few more polishes and it's off again.
On another note altogether, tomorrow I'm attending a wedding of a dear friend's daughter, a lovely girl who was my daughter's best friend for a long time. I hate parties and social occasions, but this one, I'm looking forward to. The group[ of kids who used to sit around in my house and learn science have all grown up - I'm so proud of them. It does make me feel old, though.