I'm pretty sure we trained jab-cross when I did karate (red belt in Chuck Norris' UFAF in early 1990s), but I've studied a lot of other styles since then, so can't say for sure, and I don't remember any of the UFAF forms. We were also learning a little bit of BJJ back then, so it wasn't exactly “pure” karate, not that it ever really was (Chuck Norris' version of Tang Soo Do, which itself is an amalgam of Korean and Japanese styles).
Punching to the head was illegal in a lot of tournament styles back when I was studying karate, I'd imagine they don't practice jab-cross combos much. I have no idea what the rules are today. I gave up on karate when I discovered kickboxing, really no comparison when it comes to effectiveness.