Yeah I definitely see recurrent themes in
It. As I've read King spontaneously and out of order, I don't know if they began to appear here or in the other novels first, but it's definitely noticeable. I'm hooked with the main storyline, but I'm currently on the second interlude and those are a little bit dull. I can't wait to get back to the actual story with kids or now adults returning to Derry.
I read them all in a go. Wasn't planning to, but I guess it shows I really like the series. As I said, I think these books differ enough to prevent it from becoming monotonous. For me troubled blood is at the top by a wide margin because I think all the elements are good (the main case, the sidecases, character development, the variety of themes etc.). Career, Silkworm and Cuckoo are about equal for different reasons. I slightly prefer Career of Evil out of those three. Lethal White was solid but nothing more for me, I agree some editing would've/could've made it better.
I felt the characters—all of them—were just done perfectly believable in
The Silkworm. I guess publishing industry was way more well-known to Rowling than, say, the music industry, and I felt she excelled at bringing it to life in that novel. That, and I thought she nailed the relationship between Strike and Robin in that book (she also did it in Troubled Blood, which is largely why it's my second favourite book in the series and why I stayed up until 5 AM on my vacation in another city to read a couple more chapters before going to sleep).
I should re-read
Career of Evil, as I don't remember much from it, but given my to-read list, my upcoming trip to a bookshop on Friday, and my to-reread list, I doubt I'll get to it anytime soon.