It is very common practice on the east coast of the US. I, however, despise it. It has it's uses - especially on very large projects or projects with unique connections. Fabricator input early can be critical for coming up with a really efficient design. But generally speaking, I find it's more work to specify all the loading and then review the calculations than it is to just do it myself. There's no real cost savings for the engineer, though shifting effort from design to CA can have benefits for scheduling if your firm is good at managing them. IF.
I have a clause in my proposals and service agreements that states that I reserve the right to delegate certain specialty aspects of a structure in accordance with standard industry practice. This include, but are not limited to, steel connections, open web steel joists, metal plate connected wood trusses, etc.