Anyone who really uses UML to Illustrate or understand code?
I pretty much always just get more confused when I see such a diagram.

@norman70688 yeah, but what's the point of it If you already understand the code?

For new developers and high level understanding.

my boss really likes them

Isn't it the point you first make diagrams and then code? Makes a lot of sense when the diagrams aren't made by the dev but by e.g. a solutions architect.

We use it to map out the basics of the customer requirements, in almost all the cases, the customer has some sort of business rules to model at the start.

Using multiple, we make a domain model of those rules.

We than use that to kickstart our development.

However afterwards, they're no longer maintained as by than, the domain so to say lives in the application. Besides, most ide's can generate those uml 's if you need them afterwards

I only use them for communication between developers. Its realy nice on whiteboards but Iwill never persist and maintain them because that's just more useless documentation noone reads. Also don't enforce "right" uml. As long as everyone understands what is drawn it's unimportant to use the exact style. Ilike the simplified style that robert Martin uses a lot. https://goo.gl/images/bD3YSG

Automatic generation for other devs. I'm more of a get in there and debug cases to understand the code. This could be used during requirements though. Mapped out a database using a similar method.

I do. I use UML to design my software components. It helps me to create a proper, loosely coupled design. I also use it to model complex interactions and communication flows between several systems or components. Or design complex processes. And I like to use it for functional design too. In my opinion it helps a lot to truly design upfront instead of 'designing' it in your mind and immediately start coding.