Chances of getting banned with 5 phones?

I have been hearing a lot of different things about how many phones you are allowed to use per app. From what I have read you are generally safe with 3-4 phones and 5 phones per account might be pushing it. Others say it does not matter how many phones you have its all about luck. I am basically wondering if you were to get banned for using too many phones would it be permanent? What would be the worse case scenario for your first offense? How long generally do they ban you for? Thank you for any info.