What exactly affects push notifications?

So basically here is my "issue", unless it's the same for everyone:

What would happen is every, oh let's say 10 minutes whenever someone would text me I would almost immediately get notified of it. And then all of a sudden push notifications stop working (I use iPusher to check) and whenever someone would text me then I would get the alert around 5-10 mins later, when the push notifications are working again. This process would repeat, often randomly.

Does this happen to everyone?

I am on iOS 6.0.1, iPhone 5 Black 16Gig for Sprint, using my WiFi, not the cellular data.