Lynn,
I agree with your approach. It sounds very similar to how I dealt with things when I was an ADI. After I qualified I was with BSM, so they were not the cheapest and I never entertained the "How few lessons?" approach. Indeed there was two pupils who I recall that I advised should not bother wasting their money as they did not have the right attitude
I was fortunate that after I left BSM, my car training was carried out as an addition to the LGV training that was my day job, so I was not under a lot of pressure to get a huge amount of hours/income per week.
I taught quite a few who were Medics, so had the inteilligence and dresire to drive safely, also a few family members of freinds and most commented that I taught them to drive, not just pass the DSA test. I'm dismayed that parents seem to think all they have to do is pay money to the instructor. After all parents and peers are probably the biggest early influences on driver attitude.
I think the DSA test/qualification needs to be changed. I particularly like the idea that new drivers are limited to lower performance vehicles. This could be relaxed if driving with suitable experienced supervision (to allow them to drive family car with parents or other experienced drivers). I think high speed roads should be part of the test or at least a compulsory part of training, as should practical skid control. The test should be longer and stricter criteria applied. This will of course increase costs and possibly lenghten the time before a driver was able to sit the test, hence getting more experience.
Another possibility would be that learners should have to be supervised for a set number of hours before and after the test. Even though I was able to drive and have a lot of experience manoeuvering a wide range of vehicles well before I was even 17, I did not sit my test until about 8 months after my 17th birthday. That time was spent driving under supervision at every opportunity, not just locally, but even whilst in Yorkshire on holiday and I'm sure I drove part of the way down from Fife. I'm sure this improved my driving as I gained the ability to judge many different situations before I was let loose on my own.
I also thing novices need to have the attitude that driving is a privilge, not a right, also that a car is a deadly peice of equipment and should be treated with respect.