Interesting arguments.
For me, I don’t like to change the speed, 1.0x is the best. Or else you won’t get to enjoy the whole anime.
Sometimes I skip the OP and ED but if I have time to spare or if I really like it, I don’t.

I didn’t like Mushoku Tensei after watching 2 episodes and I haven’t watched Eighthy Six so for those, I cannot really say anything.

Sometimes the animes bore me, so I don’t get to finish them. I think there’s no need to speed up if you don’t like what you’re watching. Just move on to another anime. Maybe in the future when you’ve already changed your taste, you can watch it again and finish it.

Some scenes I like, I rewatched a lot. And some animes that has an upcoming new season, I rewatched the previous season so I won’t skip a detail when I watch the new season.

But anyways this all depends on the person watching. These are just my opinions 😅