All of the above?
I read series in order, out of order, skipping volumes, ending when I get bored, all at once, spaced out over years, with other books between, binging and purging, etc.
Really I could have stopped that sentence at "I read.". Mostly it depends on my interest level and the availability of the books. With ebooks I'm more likely to read things in chronological order and have access to entire series, but it never bothered me in the past to skip around.