When reading two column PDFs on an iPhone I generally hold the phone in portrait and zoom so that a column fills the screen. The makes the text large enough but to read straight through is a bit complex. First you need to scroll down to finish the column, then up to the top of the second column, down again to finish the second column, and then onto the upper left of the next page.
It seems that apps could automatically advance in this pattern. I've tried a number of readers that do some form of advance either by scrolling between pages horizontally or vertically or by a tap like eBook reader but I haven't yet found anything that advances in this pattern.
Has anyone made such a thing?
Reformatting for mobile might be an acceptable alternative, as in this question Is there a PDF reader that formats for mobile screens? but so far I've had bad luck with the reformatting losing markup and inline images.