Well yeah, I'd always thought that was it for the YF-12 firing tests too, until I started looking into AGM-76.
I've now come across references to the 10 XAGM-76 tests from YF-12 a few different times, and I am curious why I never see it referenced in most
sites discussing the YF-12 test program.
Very recently declassified material perhaps?
I can see how the nuclear strike mission would be subject to a lot more secrecy than the interceptor mission.
Wikipedia is iffy, however Encyclopedia Astronautica is an exhaustively well-researched resource, and they've never led me wrong before.

