Over many years as a indie developer, corporate developer, architect, engineering manager, product manager, technical founder, and CTO, I've never found the specifics of UML (which arrows and box types mean what, or its distinctions between different types of containment and relationships) to be useful. I've never been in a room with someone who admitted knowing UML, or where UML made a discussion shorter or easier. I've never seen architecture diagrams or sequence diagrams, in whitepapers, technical documentation, or engineering discussion, use UML. I'd hoped that at the least UML would introduce a shared vocabulary, but within my experience it hasn't.
Reading Fowler's “UML Distilled”, on the other hand, did teach me a lot about software architecture and design, and it also taught me to read the rest of Fowler's work, which has been equally rewarding.