NOTE: You will hear conflicting reports even from different people within Facebook as to how all this works. The truth is; it’s really complex, most account reps don’t know, most developers don’t know, (#MachineLearning), and algorithms change all the time.
The best approach is always to:
think logically about whether the advice someone is giving you even makes sense based on Facebook’s incentives,
test it and see if it works to improve performance, then
update your assumptions with what you learned (and we’ll keep doing that in this post as we learn more!)
Forget what you, as a marketer or an advertiser, want for a second. What does Facebook want?
The answer: to make more money without pissing off users.