It's always a roller coaster ride, so it's really a balancing act of suffering and triumph. I believe Walt Disney put it best when he said "for every laugh, there's a tear". I live by that rule.
I don't really know a thing about gag-comics, but I know in long-running plot, there are rules. If everything is goofy and silly, it becomes boring. If everything is suffering and torment, then it's emotionally draining.
It's important to remember that after a character's lowest point, they can only go up (if they live of course). I think that's how the Korean manga artists do it.