That may have been location dependent. In the my school in the 90s it was optional. I didn't take it because I didn't want more recruiters calling me, so I'll always be curious at how I'd have done.
In my school in the 80’s it was optional. I took mainly as SAT practice, then got an endless stream of recruiters calling me. I was the only one I knew (my group was all college track) who took it, got a 99 and did not find it useful to improve my SAT