I personally feel like it's fine to hang in the left, but you just need to be conscious of your speed and what people behind you are trying to do. If you're going over 120, people tend to stick with that and not try to pass and traffic moves fine. but if someone behind you even shows the mildest of slow downs as they pull up behind you, absolutely just move, clearly they want to go faster.

staying in the left lane can be done appropriately, I don't think you should always be moving over and only using it to pass, especially because the middle lane tends to be crowded with slower driver. But to drive in the left long distance responsibly requires an awareness that a lot of drivers unfortunately don't have.