I took AMA a decade or so ago with a guy who actually was involved in taking down all the shoddy driving schools and while I have deliberately let poor habits sneak into my driving

, I feel like I do have the basic skills to be a reasonable driver.
Like you, I drive a vehicle that isn't great for teaching on (Acura TL 2012 SH-AWD and previous to that, another huge tank sized sedan), though I have spent lots of time coaching and teaching my wife. Let's just say that I haven't been very amused by the quality of a few highly ranked driving schools' quality of teaching. I'm not going to name their names, but essentially a few shave down costs by having students drive students home. In theory not a problem because it's still driving, right? Unfortunately, most of these situations involve about 1/3 of the entire lesson on a Deerfoot/Crowchild/Glenmore etc. and not really learning anything. I personally think a huge chunk of the lesson is wasted. Furthermore, my wife is still not even confident driving on roads and seems more terrified of other cars than before. I am not amused at the outcome of these "cheaper" alternatives and my wife has gone through not one, but two of these schools.
This is perplexing to me because she had a decent set of driving skills and knowledge prior to these schools. I probably spent 20 hours with her in my cars and felt she was quite ok. I had originally requested her to go to a driving school to refresh her driving knowledge, drive in a car that is more reasonably sized than my tank (after I changed cars) and learn proper driving technique and habit rather than from me and pick up my bad driving habits. I feel like after both schools, her confidence is shot. I personally think AMA would have been a better choice over trying to save a few hundred bucks. Not to mention some BS scheduling issues with the other school which made my wife lose out on the last few lessons + borrowed car for lesson (oh believe me, we've been giving them an earful).
IMO, there is no problem with us being the individuals sitting in the passenger seat while the other person practices and gets hours of practice before taking the exam. But us being the teacher? I'd get a good one for sure and not save the extra money.
I'm learning this the hard way. Un-teaching bad habits isn't easy.