That's why I'm "pro-boredom," in a sense. If you let yourself dismiss a scene when you're not enjoying it, you may never discover what's enjoyable about it. Putting in the work of paying attention pays dividends. Of course, sometimes it yields nothing, but that's why you need to get good at it. If paying attention to something boring feels like pulling teeth, you'll never do it, and you'll miss a lot of great stuff.
And it's not like you're "wasting your time" by properly paying attention to ten minutes of atmospheric scene-setting in a two-hour movie. You've set aside two hours already. Make the most of them.