That's quite a hassle to make a whole page with just one part animated, especially when you find an error and have to fix it. That would mean redoing the whole thing and then wait for rendering again.
Breaking it up in parts gives it more flexibility. Luckily, Tapastic doesn't divide the pages with a gap, but "fuses" them all together, so I made use of that feature to create my illusion.
I've done comics in Flash before, gifs, animations, I've even done two Visual Novel (demos) in Flash too, etc. It has its advantages and disadvantages. I've started combining gifs and static images just recently, initially I didn't plan to animate SAB, (otherthan the Visual Novel) but then I was like "hey why not".