Someone has to have brought this up before, but I didn't see it.
When I first started using Waze, I thought the notifications were cool, but then I realized, it's not notifying me of reports on my route, it's just notifying me of reports with the 5 mile radius. This is a horribly inefficient way to assist the user to make an educated guess of the traffic congestion either on their navigated route or in the direction they are going.
My suggest would be to narrow the notifications to the ones closest to the user's navigated route within 5 miles ahead or the reports that are in the same general direction that the user is traveling. Almost never have I gotten a notification of a problem ahead in time to make a route change.
I basically travel 2 main roads everyday to and from work and if I could be notified at the stop light of traffic that's building ahead, I'd have the option of changing my route even before Waze notices the problem.