This is one of those nice to have’s
On complex pages I spend 10-25 seconds every time I open the editor or switch pages getting back to what I was working on (opening groups in the element tree, hiding/showing elements, etc), before I can get to work. Usually, I continue where I left of, so I do this pretty much every time, and for pages with a lot of content this can take some time when you add it up.
A “remember editor state” option would be practical, to pick things up exactly where you left of. It would let you switch between pages etc, without having to navigate through all the elements one more time.