I tend to see breathing exercises as a complication to movement. I think it can be as confusing as helpful and not many people do it well. Fewer explain it well.
Agreed, when you're trying to get people to be conscious of all the mechanics of their breathing on a level that most people never think about. OTOH, I've found with some students that when practicing something simple like suburi, they do better if you just tell them, "Breathe in as you raise the sword, breathe out as you cut." Why is that? Simply because it means that they ARE breathing, and not unconsciously holding their breath as the try to get their body to do the right thing?