From Book 2 onwards I took a very different approach to speed and the way itemisation works. The speed of items is 'drip fed' in a more formal way so that the speed of items stays consistent for each stage of the book. Therefore, it is very hard to fall behind in speed and find yourself struggling.
Book 1 was obviously the first one I wrote and a bit of an experiment - that was successful in some areas, but in others probably a fell a bit short. However, like I said, you can use the Italian edition list of changes to 'amend' your book with the balance changes.
These are largely quality of life improvements to make some items stronger, have more useful stats, and reduces the difficulty of some fights.