Haven't used AdMob SDK, so not sure if the setRequestInterval is the only solution. By default, the apps in android are not killed when you press back button or home button. Android platform takes care of closing the app if there is no more memory available for running other apps.
You can try checking if the app is in foreground and then make the call to admob sdk.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.