(I don't know how much you've read) but there is a natural cut off point in book 3 that even though isn't half way exactly could be moved. Also after 2,- 3, 4 and 5 all take place very close with very little time between each (2 of them aren't even split by time but location, which I hated), the story spreads even further apart not just in location but in the characters objectives that it becomes sensible to do it this way, (also explains why one of the series in the future is adapting to books.
It is great I think anyway as there is so many characters that are underdeveloped that it could really help. I don't think they will have many more charaecters than they would have if they were just doing 1 series but I am still glad, series 2 really grinded my gears with the pacing and such and just cutting to stuff that isn'tt relevant untill further episodes. Also this is 100% taste related but it depends about what you liked from the book as to whether you liked the adaption of book 2 as it really made choices early on that they just lost entire sup plots and characters and for some fans that was what they were looking forward to the most, I think that will help that enormously
