I take it this is the built in Garmin ?
Unfortunately the standalone Garmins often do that as well. I've had my standalone try to take me off a motorway, down the sliproad, up the sliproad, feeding me back on the same motorway where the motorway bends at a junction.
All I can suggest, if it's an option, is to ask it to offer more than one route and check them out. I know they have fastest and shortest.
I use Android Auto Google Maps for traffic and a more comprehensive database of places.