My NASDS (anyone remember them?) course, back in ’74, was very similar to what Progrower described, but there was only one shop in the area so we had to really be on the ball to attend classes. I liked having part classroom/part pool every evening - besides the theory, we’d talk about what we’d be practicing that same evening and it wasn’t overwhelming at all. I think it was about 6 weeks long, followed by shore entry for Dives 1 and 2, then up to us to schedule our last two dives from a boat within a month or two - that part was pretty flexible.
I’m still getting use to this new-fangled eLearning method - used it for AOW (although my original course gave me the equivalent of AOW knowledge and experience, and more), Rescue, and Dry Suit certs.