This is the real conundrum. To me, the whole crux of OW diving is and has been trim and buoyancy. I first learned to dive without the benefit of a BCD, so it was paramount from the very beginning, especially in the Keys where long spined urchins covered the bottom. It's been my experience that once trim and buoyancy have been achieved, then diving becomes simple and easy, with most solutions becoming intuitive. After a short mask clearing class in waist deep water, trim and buoyancy is the first skill IU teach on scuba. Every skill after is then taught while trim and neutral. It's the basis on which everything else is built. Boy do my students look like seasoned divers when they finish. It doesn't take longer than a kneeling class either.At OW level, it doesn’t matter whether divers have perfect trim or can dive on Nitrox.
The first thing I check when teaching students an advanced course is their mastery of this. If they weren't my OW student, I often spent a lot of time just getting them trim and neutral. If open water divers don't flail, then neither should advanced divers. Quite often I would have students want to take a trim buoyancy course. I was more than happy to teach it, but it didn't result in a card. Why? I see it as a remedial course for skills that should have been learned in OW. It's like certifying someone to be a "boat" or "shore" diver. All of that should be a part of OW and needs no further certification. Not sure about certain skills? Not a problem and there's no shame in that. Just hire me as a coach for a day or two. Tell me what you want to learn and we'll go from there. Just don't expect a card for learning remedial skills. I mean, do you really need a card to inflate an SMB at depth? There's at least one agency that offers that. Wow. I guess that's why I didn't teach for them. FWIW, that was a part of my advanced diver course.
Not to mislead you, at one time I too was pissed at instructors who taught on their knees. It upset me that they instilled such a bad habit into their students. A habit that can take a lot to break should I teach additional classes to their students. Yeah, they made me work harder, but then I mellowed. Dive and let dive. Teach and let teach. Post and let post. I came to peace with the mantra: "Not my monkeys and not my circus!" I would see their students diving with the look of near-panic in their eyes and dive on. Yes, I had to rescue a few, but that's on their instructor. I learned not to make a single comment about them on the boat and I'm content to simply set the example.