Are you sure waze doesn't learn routes? Or at least reduce the "cost" to locations on your way to your destination? This isn't the experience I have. I'll explain:
I regularly drive to one place at different times of day (I called it "work") using my own preferred route. This is west of where I live. Waze seems to have now "learnt" that I prefer that route, and sometimes the alternatives seem quicker. The route uses a major trunk road - the A12.
However, recently, I asked to route to somewhere else, in the other direction, about 50 miles away to the east. Waze took me on part of my regular route to work, via the A12 west of where I live, rather than a junction with the A12 east of where I live actually on the way. This route was a few miles and 10 minutes longer than a better route.
Waze knew about this route because when I asked for other routes, it only listed one, and that that was what I would regard as the proper route.
So in a nutshell, waze shows me an inefficient route that uses part of my way to work, and when I ask to show me routes, it shows me just one route, a sensible one.
So it appears to be behaving as if it attributes a low cost to locations along regular routes, in preference to what it knows to be a correct route. It added only a small percentage to the time and distance travelled. When I tried routing to other locations along the way to the second route, it stopped using the "silly" route when the destination was nearer home.
Running Ubuntu 12.04 / Windows 7 / iPhone 4s
Wazeing about 250 miles a week!
Area Manager for South Essex (UK)