I'd think it's pretty common. It's not necessarily "on-call" as in "waiting for you", but depending on what you do, you end up having contact with different law

I'd think it's pretty common. It's not necessarily "on-call" as in "waiting for you", but depending on what you do, you end up having contact with different lawyers in different areas. And in doubt, it's better to stick with someone knowing your situation. Like, I had a few issues with the last place I rented, and during that, I entered the Mieterschutzbund, an association for tenant protection. Through this, I can get access to an hour of consulting with an expert from the association as well as one or two hours of a lawyer specializing in tenant laws. This doesn't take much longer than 1-2 days. So I guess I have a tenancy lawyer on call.