Most scuba agencies have adopted
Bloom's mastery learning/standards-based approach, and in doing so, time has become unimportant. In education circles, we talk about it this way:
In traditional instruction, time is the standard and learning is the variable. In standards-based learning, learning is the standard and time is the variable.
When I set off to get cave training, I had been doing technical diving for several years, I was used to all the equipment (except reels, spools, and arrows), and I could do all the kicks. The first day was all academics and land practice, and then it was cavern training at the Ballroom at Ginnie Springs. As we set up our gear, an interested onlooker came by and talked with us. When he learned it was a class, he said he was interested in learning cave diving himself, so my instructor gave him his card. Later on, while we were doing my class, we saw that diver in the open water area with his wife. They were working on diving skills. Specifically, they were kneeling in the sand and practicing mask clearing.
Do you really think it should take that new cave diving student the same amount of time to complete a course as it took me?
The published course guidelines are in my view an estimate of what it should take. As for me, I went straight through apprentice in fewer days than advertised. I then went out using my expiring apprentice card and got some more practice. When I felt ready, I went back and got cave certification. In that case, it took me an extra day because I mucked up taking the reel out of the Devil's Ear in extremely high flow and had to come back and prove I could do it right. Learning was the standard--time was the variable.