I work for a very object-oriented customer, and I find class or object diagrams useful (for example, to take notes about an unfamiliar system being explained to

I work for a very object-oriented customer, and I find class or object diagrams useful (for example, to take notes about an unfamiliar system being explained to me, like expressing precisely and concisely that Permissions are granted either to Employees or Groups of Employees, and not associated to the Employee's or Group's parent OU directly) much more often than sequence diagrams (typically used to document boring and straightforward odysseys of method calls through layers and layers of indirection, not interesting protocols). All non-bullshit UML diagram types are going to be valuable sooner or later in one's career; basic familiarity with all of them is a useful language skill.