The name of the Route profile does not specify how the route is calculated in general. Therefore it is possible to select "Fastest Route", but getting a route which takes longer to reach the destination than with the selection on "Optimal Route".
For example, the Route profile "Fast" doesn't mean you get the fastest route between A and B. The app is calculating the route by comprising streets, that allow high speed limits, such as highways and motorways.
There are four Route profiles to choose from:
Short: The shortest route will be calculated (also including dirt roads). Included are city centers and restricted areas. Therefore the shortest route is not necessarily the most timesaving route.
Optimum: This calculates the most direct route, which can also include city centers. Restricted areas are being avoided. Therefore the optimal route is not necessarily the most timesaving route.
Fast: The app tries to calculate the route by comprising it mostly via motorways and highways. If you forbid highways in your route profile, the app tries to navigate you alongside a highway. Please mind in this case, the selection of the fastest route can lead to detours, as the app tries to navigate you as close to highways and motorways as possible.
Scenic: This route profile is suitable for motorcyclists. Highways and motorways are being avoided. The app calculates a route with more demanding requirements (many bends, hills, valleys).