Notebook style development is considered an anti pattern in most situations for this reason. It is too easy to execute out of order. Even the original parent of this thread said they recite the entire notebook every time to ensure they catch these issues. But, it’s not perfect and you can have leftover state this way too if you’re not careful.

My guess is that this is the reason the GP here is so against them. I find them helpful for data exploration, but that’s it.