I just finished a brief course in humor writing at The Loft in Minneapolis, taught by Tiffany Hanssen. She stressed knowing about the characters who populate humorous sketches and stories. Character development is important to speculative fiction, too. I will do a page or two on my primary characters and a paragraph on the minor ones. Tiffany, however, says that the pros in humor will complete ten pages or more on their primaries and a page or two on their secondary characters.
They write these monster volumes of material on back story, job, emotional triggers, likes, dislikes, wardrobe, design and decoration preferences, props that they regularly use, stereotypes, facial expressions...getting a bit carried away. But that's the point, they get carried away with creating complete characters because they know that somewhere hiding in the bushes of that character are the seeds of humor that they can plant and grow. Remember that this is done for every character in something as short as a two minute sketch. They want to know it all.
All of this for humor, thought I? I write big important stuff! I deal with world changing ideas! And I have to create real, believable characters who pull readers into the story, immerse them in my created world. I knew that I needed to know as much about my characters as I could, but I have often stopped at knowing a character's physical or emotional limits, and don't care whether they cheat at poker (just because there's no poker game in the story). The reader doesn't need to know everything, but the writer does. A little nugget of knowledge, though, might inform the reader more fully about a character, and do it with an economy of words.
So, I was humbled. Now I will free associate until I know my characters completely. I will list and I will categorize and I will delve until there is no heart spring unwound and no zit unpopped. Eeeww. Just...just know your characters.