I noticed a subtle, but significant improvement in El Capitan's Contacts app this holiday-week Monday: if you have a full address copied, you can now paste it in one step.
It didn't use to work that way. In earlier versions of OS X, pasting anything into an address field in Contacts or Address Book put the copied content in whatever field you were in. That led to this work flow for me:
Copy the address (necessary for apps that without calls to Apple's data detectors in OS X), go to Contacts, insert the cursor into the street address field, and paste, as shown in the screenshot below.
Address paste the old way
Then, you highlight and cut everything but the street address (extra space included), and tab to the City field, and paste again, as shown below.
Personally, I'd then double click the zip code, cut, delete the bonus spaces and state, tab to the state field, fill that in by hand, tab to the zip field, paste, and boom! Address added in an absurd number of steps.
As noted above, when Apple added data detectors in Mail—and to a much lesser extent Safari—I didn't have to do the copy/paste dance as often, but every once in a while, you'd still get an address you needed to add to Contacts by copy/paste.
Which is what happened to me today. Only when I went to Contacts, inserted the cursor on the Street Address field and pasted, a magical thing happened: everything went where it should go in one fell swoop.
Address pasting like it should be
I'm fairly sure this is new for El Capitan, but I'm just pleased as punch to see it.