Is there a "rule of thumb" for pairing a lathering mug/bowl with a given brush? I'm currently using a Kent KB4, and a largish coffee mug. It feels like the mug is too tall, and possibly too narrow - but then again I'm not claiming to have a great technique.

If nobody's thought about this before, but has a particular brush/bowl combination that works particularly well, I'd appreciate your taking a moment to actually look at what you have. How does the height of the bowl compare with the brush length? How is the width compared with the (flared) brush?