Are requesting test ad serious ?

Hello everyone, i wanted to know if requesting real ads from admob for the purpose of testing and developing considered invalid activity or not ? What do you guys usually do and has anyone faced a problem from it ?

not advised,
I have read in this forum somewhere that they got their admob a/c banned because of invalid activity.
Suggest to add your device as test device
and you should be very and you can test just like clicking on real ads