Ability to choose a route vs. choosing a destination
I take the same route from work to home everyday because it's the fastest way to beat the rush hour traffic flow. I always route to "home".
Often, I am in the same general area as my workplace and trying to get home and waze puts me on the same roads that I would take take on my work -> home commute. But just as often, this isn't actually the faster way. It does this because it has learned my route preference for going from home to work.
If, when heading home, I could choose a route (ie, "work to home") rather than just a destination (ie, "home"), then Waze would know to send me home on my work -> home route when leaving from work, and it would know that when I just choose "home" for my destination that I want the most efficient route it can find, regardless of my past driving preferences.