Sequential reading of text is very inefficient.
Reading is def not 100% linear, as I find myself skipping ahead to see who is talking or what type of sentence I am reading (question, exclamation, statement).
There is an interesting discussion down thread about ADHD and sequential reading. As someone who has ADHD I may be biased by how my brain works. I definitely don't read strictly linearly, there is a lot of jumping around and assembling of text.
My initial reaction was to say speak for yourself about what reading is or isn’t, and that text is written linearly, but the more I think about it, the more I think you have a very good point. I think I read mostly linear and don’t often look ahead for punctuation. But sentence punctuation changes both the meaning and presumed tone of words that preceded it, and it’s useful to know that while reading the words. Same goes for something like “, Barry said.” So meaning in written text is definitely not 100% linear, and that justifies reading in non-linear ways. This, I’m sure, is one reason that Spanish has the pre-sentence question mark “¿”. And I think there are some authors who try to put who’s talking in front most of the time, though I can’t name any off the top of my head.