Not sure I understand why you would want do have it learn your alternative routes. I certainly don't know average speeds of all segments of roads better than Waze does. And I don't know how anyone could claim to. People always like to claim they know the streets and traffic better than any GPS possibly could, including Waze. Problem is, that is not true, and could not be true, at least not once Waze actually has a good amount of data for your area. The only time you would know more than Waze is when it doesn't have enough average segment speed data, and/or turning restrictions for your area's intersections are not yet correct. Once the restrictions are correct, it doesn't make sense to do anything except trust Waze's route, even when you think it's being stupid. Following Waze even when you think it's leading you on a poor route just means that that poor route will be getting better average segment speed data as a result, and in short order it will no longer bring you on that poor route, as better routes will become evident. You teaching it your "better" alternative route isn't going to help give you the optimal route anymore than driving poor routes will.
If you just want to continue driving your same old route regardless of how optimal it is, what's the point of using Waze? The whole point of using Waze is supposed to be to get the optimal route given current conditions. The optimal route isn't necessarily what you think it will be at any given time. The optimal route will always be the one that takes the shortest amount of time. So you take the average speeds of all segments, factor in current traffic reports, and calculate the shortest travel time from that. You will never be able to do better than that. A computer will always do that better than you, when given all relevant data. That means Waze wins, unless it has insufficent data. Your personal alternate routes are irrelevant as far as I'm concerned. And you thinking they're relevant is rather puzzling. Because you do not and cannot know better than the computer, unless the computer is data-starved.