Yes, Breidscheid, Karussell and Schwalbenschwanz (with the "Little Karussell) as second turn) aren't really spots to push hard and gain time.
Breidscheid is difficult. You should NEVER go on that concrete patch / kerb! Brake a bit earlier, coast or trailbrake until your car points straight and is stable and then go on the throttle again to focus on the uphill righthander.
Karussel: The difficulty here is to brake until you're settled in the banking. Brake too early and you lose a lot of time, brake too late and you won't make it. If you are not 100% secure on that it's indeed faster to just go around on the outside and focus on the exit!
Regarding the exit though you can go full throttle a lot earlier than you would think and gain a lot of time on the next uphill and full throttle section!
Schwalbenschwanz: brake a little bit early and on the very left for the right hander, then concentrate on a good coasting line for the left hander so your car is very stable when you approach the little karussell. Brake a little, go in the banking and slam down the throttle the moment the camber pushes you around.
In a GT3 you will be jumping off at the exit and gain quite a lot with early throttle.