I drive when and where I feel comfortable. Usually at or slightly below the speed limit. I'm mostly optimizing for making the minimum number of lane changes once I get on the motorway. Preferably that means as soon as I get on the motorway switching to whatever lane will take me directly to the exit. A lot of people do what you do. Doesn't bother me a bit. My logic is no one is really actually getting anywhere any faster anyway. They're just increasing risk for barely any benefit. Changing lanes seems to me like the most likely time to have an accident, so the people who insist that driving at the speed limit isn't fast enough and that they must change a lane to go around me and then change back again taking a small risk twice for the privilege are just impatient.

As the old saying goes "everyone who drives slower than you is an idiot, everyone who drives faster than you is crazy".

Fun fact: I also take routes that minimize the number of times I have to turn into oncoming traffic and/or judge gaps where the landscape gives poor visibility of the traffic, so long as the detour is no more than a few minutes.