Sequence diagrams are great. Any time there's a multi-stage interaction with multiple independent pieces involved, they're hard to beat for communication. It's

Sequence diagrams are great. Any time there's a multi-stage interaction with multiple independent pieces involved, they're hard to beat for communication. It's not like UML was based on bad ideas. There were just too many cases where the added value was less than the added cost. But when a diagram does add net value it's great to have conventions already.