Match Format To Audience
Sudoku works well for readers who want repeatable logic. Word searches are approachable for themed collections. Mixed books are useful when the audience benefits from variety.
The best format is usually the one your reader can understand immediately.
Plan Difficulty Progression
Easy starts reduce friction. Medium puzzles carry the main body of the book. Harder puzzles make sense near the end or in a clearly marked section.
For classroom and senior activity books, clarity often matters more than puzzle density.