Different operating systems behave differently. For Android, we recommend using  three to five creatives with a minimum $500 daily cap.
On iOS, consider starting with a daily budget cap of $50 to mitigate the risk of overspending. Cost per mille (CPM) billing with Unity on iOS enables lower daily budget caps than previously available.
Using lower daily caps at the beginning of new campaigns will help advertisers avoid overspending on high effective cost per install (eCPIs) before real performance can be observed. After several days, advertisers can increase daily budget caps to achieve more scale after the initial exploration.