This is actually quite difficult to control, but there are a few strategies you can use.
I deliver ads to all of the boards you’ve chosen in an indiscriminate way. If you’ve read the detailed article on programmatic advertising, you’ll know that boards actively request ads of me, and I respond with your ad if it matches your campaign’s conditions. The main things I look at are:
If these conditions meet, then an ad will attempt to serve. The problem with this approach is that I will naturally bias towards the least expensive ad opportunities, and also towards the most frequently requesting boards (i.e. the most ‘available’ boards).
You’ll notice that your campaign will both deliver more ads (and more budget) towards the boards that are cheaper and more ‘hungry’ for ads.
It’s not really possible to mitigate the effect of the board’s availability, however it is possible to reduce the impact of different boards’ costs. If you find that some boards in your campaign are either underperforming or overperforming, I recommend creating a new campaign with those boards, and removing them from the existing campaign.
Why? Because moving boards to a new campaign means that you’re carving out a set budget dedicated to those boards, and I won’t have other cheaper/more-available boards to distract me from delivering to the boards you want.
You should end up with 2 (or more) campaigns depending on how many times you repeat this process:
I’d also recommend modifying the budget and spend rates of both campaigns so that you’re getting the rate of delivery that you’re comfortable with.