Interestingly 幻獣調査員 is the only one where I actually did this so far i.e. last summer after it started with 13.5 lookups/page in the first 10 pages 
. Other ones I did not even try to start in the first place.
But as @cat already said, books tend to get easier after some time. らせん e.g. for me started in the 12+ range and after 100 pages went down to 8+ lookups. Otoh it all depends on how many lookups you can tolerate.
