The most difficult pages I have to work on are any panels, pages and certainly splash pages that involve drawing a lot of distinctive background characters. It's fine if I have to draw the main cast or people with actual impact on the story. But there's a tedious aspect to drawing random background characters. Usually I'll just try to cheap my way out with basic outlines and stuff but sometimes you got to actually draw something.
And this means working with character designs that I don't care about because other than this one page, they will never appear again. They have absolutely no impact whatsoever so there's no enjoyment or closeness to these background characters. I want to focus on drawing what actually matters and I don't want to put any distinction into them when that same distinction could go into more impacting characters.
It's boring and tedious because to me, it slows down the creative process. It's basically taking the same time and effort it would to draw a page but with none of the enjoyment that usually comes from it. I want to get to drawing the actual good stuff but sometimes, you just got to have something on the page to give it life.