I had a chance tonight to play a bit with this. I'm actually finding some strange things. I ran some old test code where I just recall/gate/SJ from 4 runes in a book over and over again. There are instances when I do an event macro 17 to open the runebook, and it just won't open. To test this, I wrote a container open sub that will retry opening the runebook and count failures. And behold, the counter does increase every once in a while showing the book just won't open sometimes. So if the book doesn't open, you don't change the index you're gonna goto, so you recall/gate/SJ to the same spot.
I'll do some more testing.