The fastest way to sort books in Clean The Library is not to touch every book immediately. It is to reduce wasted movement. Every book has to reach the shelf where it belongs, so a run becomes faster when you carry books that belong along the same path and slower when you create a mixed stack with no plan.
Start by reading the destination or label before moving. If a book points to a shelf zone near you, place it now. If it belongs far away, decide whether to carry it with other far-zone books or stage it in a tidy pile. A book on the floor is not automatically a mistake because books now save even on the floor. A bad drop is one you have to identify all over again.
Work one shelf zone at a time. If you are near several books that match the same shelf area, finish those first. If you carry multiple books, cycle the stack before leaving the shelf. On PC, use the scroll wheel. On controller, use LT. Many players waste time because they stand in front of the correct shelf with the wrong book on top, then walk away without checking whether the next book in the stack fits.
Use staging piles for mixed books. A good staging pile sits beside the shelf area or path where the books will be placed. A bad pile sits in the middle of a walkway, covers labels, or mixes several distant shelf zones. When in doubt, split the stack. Carrying fewer books can be faster if it keeps every trip understandable.
Shelf lookup and map notes can help with first-floor and second-floor labels, but the in-game label wins whenever a route note disagrees with the server.
In co-op, book sorting works best when each player owns an area. If two players chase the same pile, they both lose time reading and moving around each other. One player can collect and stage books for a zone while another places them. If you find books for a teammate's zone, drop them near that zone and call it out instead of carrying them across your own route.
For timed badges, clean sorting matters more than a perfect first minute. A messy early pile causes repeated label checks later. Keep shelves, piles, and routes readable from the start. The library gets easier to finish when every dropped book still has a reason to be where it is.