I think I also do this. I don't really 'skip' anything, but the assumption I made for 'webcomics' is that the panels are less detailed with the intention of scrolling. Anything I should know about will be brought to the forefront in some way, even if the characters don't address it. For example, that mysterious box in the background of the last panel suddenly has its own panel.
I read both only once, 9 times out of 10. But I do go back to reread some if I need a refresher for a story I loved. I am more likely to reread traditional printed comics. I have a collection of Tank Girl comics I go back to on a regular basis, for example, because they greatly influenced so much of my life. I have a collection of Hawkeye comics that I love, but I have only ever read them twice, max.
To me, webcomics are like TV soap operas, and print comics are like movies. I love both, but I would be more inclined to rewatch a movie I loved than a soap opera.