When should you use all placements when running Facebook ads?
Whenever you’re optimizing for conversionsA conversion is counted whenever a website visitor performs an action that fires a standard event, custom event, or custom conversion. Examples of conversions include purchases, leads, content views, add to cart, and registrations. More. It’s not that complicated.
This is the one time when you can trust the algorithm. It will make changes dynamically based on costs, competition, effectiveness, and your audienceThis is the group of people who can potentially see your ads. You help influence this by adjusting age, gender, location, detailed targeting (interests and behaviors), custom audiences, and more. More.
Don’t try to outsmart the algorithm. You will almost always lose.