Yeah, pacing is the whole game. A show like Severance gives you a clear puzzle box with immediate tension. You get a new piece every episode. The OA asks you to sit with weirdness for a long time before the payoff, which can feel like homework. It's the difference between a page turner and a slow burn that some people just can't stick with.
Totally get what samwalker means about it feeling like homework. My friend tried The OA and said she felt like she was studying for a test on a made up religion, she gave up after three episodes.