This question relies more on theory then code, it is about the AdMob AdBanner but also just ads in general which you can implement in a react-native app.
If you are familiar with AdMob, you know you can create multiple AdBanner or also RewardAds and place them in your code but here is the question:
Should I create one AdBanner and place it on multiple screens inside my App or should I create different adUnits and for each screen implement another AdUnit?
From my perspective, I do not see any difference beside that with seperate adUnits you have a better overview on which screen has the most activity and which screen makes more profit but that is all. It seems to me much more easy and gives me a better overview if I only use one adUnitID for Banners, one adUnitID for RewardAds etc.
What is your opinion on this topic?
I recommend creating ad unit for each screen, I've notice that when I use one Unit ID all the banners will show the same ad until it get refreshed everywhere, but if I use separate unit ID for each banner the ads will be different which will result in better revenue.