Sometimes, usually when I'm inking because it's very slow and tedious work for me. When I'm doing faster, more sweeping kind of work like during the sketching and toning phases, it's easier to view the page as a whole. I find working in stages helps, and stepping back for a bit between thumbnailing, sketching, inking and toning/colour.
Usually if a page isn't feeling as engaging as it was when I was writing or thumbnailing it, it's because something about the execution of the page isn't working. The current page I'm working on had me feeling this a lot, until I realized the problem-- some of my compositions were static and dull, because I was in a hurry and went with my first idea for them. When I went back in and re-drew them with much more interesting and compelling compositions, the page as a whole felt less bland to work on.
Of course, nothing is going to stop that feeling if you've been grinding away at a page for 20+ hours ~v~;; every now and then I have a monster of a page that I just couldn't be happier to be done with.