Notification Sound/Vibrate Timeout

I would very much like to propose that somehow a "Notification Timeout" feature be implemented and adjustable.

This suggestion is for those lovely friends of ours that can't seem to put an entire thought into one message and have to send 5 messages to say 1 sentence. And of course, if I'm tabbed out or in my game or trying to focus on something... what do I hear? 5 notification sounds, over... and over... and over... and over...

I only need to know they messaged me once. I only need to know that there are NEW messages... not... a billion each time they are sent.

So... Notification Timeout is the only name I can think to call it... God forbid I just forget that they messaged me in the first place, have an adjustable time-frame of when you'll hear another notification from them.

For example... They want to tell you something cool that happened in your game but have to send it in 15 short sentences, you only get 1 notification sound for that entire onslaught of verbal abuse to your account... You get so engrossed in your game that you forget that they messaged you and they try to say hi to you 5-10 minutes later to make sure you're still alive, and you then receive the sound notification for that. An Adjustable Notification Timeout.

I really... wish this was a thing in normal every day forms of communication. Nothing is more annoying than driving down the road with GPS going, getting dropdown notifications every single message from the same person while you're trying to drive, see your upcoming turn, possibly speeding down the highway at 70+ on Southern Californian highways.... just. Please... Help the world and make this timeout feature.