But you've to consider that many customers will download everything that's free. For example, if you've a cookbook in the promo phase and customers have downloaded novels, self help books etc. before and/or after they downloaded your book, you build up "false connections" to these unrelated books. The more downloads you get, the stronger will be these senseless connections. So after the promo phase you've more sales but if you can't hold them up your visibility decreases until your book is dead. Only chance is to run another free promo. The more free downloads you have, the the more "related sales" you need after the free promo phase to get connections to related books and this may take several months. With the free promo you'll take the quick bucks but boycott your long-term success. PS: It's not clear how the algorithm works exactly and this is just my personal opinion. So I don't want to say that the free promo isn't working for someone else but for me it isn't working.