Now this is an interesting shot from episode 6 of K-On!
All four characters are in the same place, and just from this one still you can get a basic idea of their personalities. On the flipside, if you already know the characters then you can definitely see that this is instantly accurate.
In general, K-On! pays a good amount of attention to these sort of things, and I think it’s characteristic of Kyoto Animation in general. Some wonder why others are so fond of Kyoto Animation’s various works, from Haruhi to Lucky Star to various Key adaptations, and the answer is care. These are not just moe blob shows with no real content, they’re visually rich with a good sense of timing and comedy (or tragedy as the case may be). K-On! is no exception.