OK, I’m a simple teacher, so I may be completely wrong. However, I assume you’re referring to incremental improvements that you might be trying to produce in intermediate or higher level students who have had significant exposure to English already.
I can’t imagine you would subscribe to the same conclusion in the case of beginners. For example, one group of my students are first grade elementary school Taiwanese kids. Many have never seen English Ietters before, and both their Chinese characters and “bopomofo” phonetic system are of no assistance for reading, writing or pronunciation of English. I can’t see myself standing in front of them with an alphabet flashcard and just letting them pronounce the letters any way they feel like on first exposure to them. If I showed them “a” and let them say “b” their chances of being able to communicate ANYTHING would be nil.
While I don’t expect many of them to ever approximate the pronunciation of a native speaker, I do hope they will get to the point where they can at least be understood by one.
Am I wasting my time and theirs?
Posted 1st August, 2010 at http://scottthornbury.wordpress.com/2010/08/01/p-is-for-pronunciation/#comment-1588.