Did King realise that the adult half of the book was inferior?

Is that why he decided to "interlace" the two time periods together for the book? I find it distracting going back and forth in time when reading the book, but considering that the Losers' encounter with IT as both children and adults unfolds more or less at the same time in the book, going back and forth, then I think King thought it was the only way to maintain interest?

Then again, the book and the miniseries does make a similar mistake when they have them as adults receiving the phone calls that bring their childhoods back to them, which in turn makes the childhood battle with IT pointless as we KNOW they survived.

So King was stuck between a rock and a hard place whichever way he chose. Muschietti separated the time periods, at least for them as children, so for those who never read the book, the suspense was higher and so it was better received in the first Chapter, but then the adult encounter was less interesting in the second half, so Chapter 2 suffered.

So the story can't win, either way... unless people like the adult half, which many do. So it's all down to taste.