Still thinking, but exceptions or not, the trend definitely seems to have changed after 1972. It's an interesting contrast to the current situation, in which the networks strongly discourage opening credit sequences at all, preferring the shows to get started immediately.
Good question. Banacek had them, although you might not count it because the NBC Mystery Movie intro played before even the teaser started. I'll keep thinking, though. (Shows in the '80s and beyond had them again, but I'll concentrate on the few years after 1972.)