An ebook promotion can generate downloads or sales that may affect a book's position in retailer charts or rankings.
However, retailer ranking systems are controlled by Amazon and other ebook stores, and their formulas can change. The Fussy Librarian cannot guarantee that a promotion will produce a particular ranking or chart position.
If ranking is one of your goals, coordinating multiple promotional activities during a concentrated period may increase reader activity, but results will vary by book, genre, price, and marketplace.
It is usually better to view retailer ranking as a possible result of reader activity rather than a guaranteed outcome of a promotion.