If "skills" don't have real world applicability, then instruction is degraded by its interference.We breathed off a cylinder (with no reg on the valve) in a swimming pool as a "confidence-building exercise." One such cylinder was put in each corner of the pool, and we swam underwater from one corner to the next, breathing only from the cylinders. (Cupping our hands to catch the air so we could sip air from the air bubble.)
It was an exercise with zero practical value, so there is no reason to try and work out how you'd do ti for "real.". It was just one of the ways to fill up the many hours of pool time we went through.
Strip out the nonsense like that, and make the teaching more efficient, and of course the pool sessions can be shorter than they used to be. Shorter does not equate to worse, just as longer does not equate to better.
That said, I think all agencies that teach underwater scuba kit removal and replacement in the pool only makes it pointless exercise for cold water divers who may not be able to perform that skill in open water. But that's another topic.