Yeah, the formula is kinda the problem, as it's, ya know, the same idea but in a different setting every time.The books effectively follow a formula from books 1-7, in that it has the formula of "children turn up at place, Olaf turns up, no-one believes its Olaf, Olaf is found out, escapes, kids go elsewhere, rinse and repeat). Books 8-13 change around a bit though - they're more contiguous, formula has changed a bit, arguably become a bit more 'meaty' in terms of theme. I'd say that 7 is the transitional point, in that it starts with the formula, but it's darker in tone, and ends with the kids striking off on their own.
And I watched to s2e6, which should be about book 8, and I didn't really notice it there (which was probably why I stopped), other than that Olaf had gotten a new member of his troupe.
It probably didn't help that I had gotten a bit used to the world and people who were weird, I suppose. The more weird you're exposed to, the less weird it seems, making it less interesting.