Adext AI is intelligent enough to know when it should do additional exploration to make sure it isn't missing an opportunity. It takes this decision every hour for each of your ads. The reason Adext AI explores is because it wants to achieve the Highest Sustained Conversion Rate (HSCR), that is the theoretical maximum conversion rate for a given ad. To do that, Adext AI needs to always be looking for the right mix of demographics to maximize the conversion rate for the entire duration of your experiment.
It's important that you do not exclude too many demographics from your experiment, otherwise you'll limit Adext AI's efficiency. If you're absolutely certain that 18-24 males will not be interested in your ad then feel free to exclude them, however, Adext AI will discover that fact very quickly and at a minimum of ad spend. For that reason, we usually recommend that you do not exclude any demographics so that Adext AI can build a strong understanding of your ads.