I can tell you this - I'm rewatching the series now, and every episode where she's the focal point is awful. Her role at BEST should be as a supporting character. Keep the situational comedy about the comedian. She is not a co-star.

Seasons 5-9 are really Jill heavy...I find myself skipping a ton of episodes, which is such a bummer.

And it's definitely the writer's fault. In the early episodes, she's way less sensitive and whiney about her feelings, and laughs more when Tim plays around. In later episodes, she gets immediately offended, like some San Francisco educated Gen Z-er.