Is it? I don't mean "reading randomly, out of order" nor do I mean skipping to the end to read spoilers (though some people, puzzingly, do just that). I mean randomly reading parts I've already read. I assume a lot of people's reading habits are similar to mine.
I don't do that and have never heard of someone doing that. I have heard of people re-reading a chapter they just finished, because they enjoyed it so much or because they felt they missed something. I've heard of people opening a favorite novel to a random page, reading for a bit, then closing it.
The only non-sequential access I ever do in novels is for reference material, things like maps, character lists (e.g. Game of Thrones), or glossaries (e.g. Clockwork Orange). Footnotes on paper are sequential-ish, I read the Three Body Problem novels on a Kindle where you tap on a footnote number to get the text in a separate window and there's close or back button to return to the original page. I heard at least one David Foster Wallace novel had some insanely long footnotes that went on for multiple pages and maybe footnotes within footnotes, I don't know how that works on paper or an e-reader in terms of navigation.
