Not really. Generally speaking, some projects use a few of them for some communication, but generally speaking, they're not used anywhere to the degree they're

Not really. Generally speaking, some projects use a few of them for some communication, but generally speaking, they're not used anywhere to the degree they're portrayed they are in classes. That said, I've seen them on white boards (and drawn them myself) or tossed some in documentation occasionally, but they're relatively rare.