I noticed this trend, on the heels of my last post, while flipping through a large stack of comics (some of the classics, some of the not-so-classics) and various websites of current artists work.
What I noticed more and more, was a tendency to use large panels to showcase the "coolest" part of the narrative or the shot that was the most fun or complicated to draw, ignoring the story beats that are the driving force of panel to panel storytelling. I'll say it in the shortest possible terms rather than trying to argue a number of small points: The size of the panel is determined by the story beat. The amount of time you want the reader to linger on said panel. The emotional impact of the content inside the box.
There. That ought to do.