Edit - What are we thinking for the Sin City graphic novels, I saw a bit of discussion earlier about graphic novels being added?
We can't really go through each case, and to be honest, it's really up to you. This is all on you. You only have your self to let down.
If an example helps: last year I read a comic book called The Rainbow Orchid [I wanted to read at least one graphic novel or equivalent]. There are 3 volumes. I counted all three volumes in 1 entry:
1, all three volumes amount to one feature length story.
2. I read the single full size comic book length version.
3. The book [set in the last century] talks about some events that actually happened, and it's kinda cool to match up and look those things up.
4. It took me about a week to read it and consume all of it. [If I didn't take in any of the illustrations, and read it like a nine year old me, I guess I could have read it in one or two sittings]
And then there was an art book, called Reading Women. I felt guilty having to count this; it's very short on words, [even though I counted at least one five hundred pages + book as one and not two, so I had leverage anyway]; but like all art books, you go deeper and deeper, and the book took a long time, really to consume. I didn't count all those other books and wiki links and material associated with this one Art book and it's master thesis; but I feel now that it warranted a place on my list. I read a lot of excellent books and this, for me, was right up there. Not much on the top, but a lot underneath.
It's really up to you. No reason why at the end of the year, you can't remove certain entries, because you know, you ought not to count it.