Is there a way to keep Maps from changing route?

I think the following is a bug in Apple Maps because I don't remember this behavior before 9.1 or 9.2:

When I enter an address in Apple Maps try to get directions, Maps will offer a first choice route (automatically highlighted) plus zero or more alternatives. I often pick one of the alternative routes because the suggested first choice involves tolls (as an aside, if you know of a way to tell Apple Maps to not even consider toll roads, I'd appreciate that too). Unfortunately, while Apple Maps initially accepts my choice, it oftentimes quietly reverts to its primary choice. It *seems* that this happens when you don't start the trip where Apple tells you to start - e.g. it starts the route at one exit of a parking lot and you exit the parking lot via another - or if the initial route tells you to go left and, not knowing which way is north, you turn right instead.

The worst thing is that Apple Maps reverts to the other route without telling you. Before I realized this annoying behavior, Apple Maps has led me to those dreaded toll roads that I was trying to avoid. Now I'm in the habit of going into "Overview" mode whenever I deviate in the slightest from the prescribed road. I end up, quite frequently, canceling the navigation and starting from scratch so I can re-select the route. A workaround - but a very annoying one.

Am I the only one who's had this problem? I've used iOS since iPhone 3GS and have not noticed this behavior at all until fairly recently - sometime since iOS 9 was introduced.

If anyone knows how to make sure a route is "locked in" (or knows of a way to tell Apple Maps to ignore toll roads in the first place), I'd very much appreciate that info.