use a ruler or paper and block out the next few lines. then just move down the ruler as you go so you focus on one line at a time. this is what I do when I'm distracted and trying to read.

It can either work well as a literary device or destroy the whole book. No in-between.

For example, the book "They Both Die at the End" (which was hated by a lot of people; we'll disregard this) used the "spoiling" literary device. I think it worked very well because that's where the story revolved--them dying in the end. It also constructed some expectations that maybe they won't die after all and the title was a "clickbait." The point is, the spoiler in the title had an overall purpose for the book. It made us wonder what led them to that fate and how they were going to die (if it was true).

What ruins a book when a spoiler is provided in the preface is the lack of purpose. It's just there to be there. And it makes the reader infuriated because, as you said, what was the point? If the author gives a spoiler important enough, then it should work around the theme of the book or at least some other plot device.

the ones I would usually shelf because then I'm "forced" to read them especially when there's no tv on the plane.