Although it happened almost twenty years ago, I remember this language situation as if it happened yesterday. I asked a native speaker of English, a young guy from South Africa teaching EFL at the local grammar school, if he could help me write up my curriculum vitae. I wasn't exactly a proficient writer at that time and I needed it to sound perfect and professional since the CV was part of an official grant proposal. Long story short, he actually wrote up the whole thing for me. And it was perfect and professional. While reviewing it contentedly, I came across a structure which struck me: I am attending an artistic school in my village and I have been since 1983.
At first I thought he must have made an error. I mean, I knew the present perfect continuous structure like the back of my hand: I have been + verb-ing + since/for/etc. So I asked him tentatively about the missing verb-ing form. He retorted that everything was perfectly all right with the sentence; nothing was missing. I wasn't 100% convinced so asked why he had used such an odd structure and not the one everyone (= coursebooks) used. I remember he shrugged his shoulders and said something along these lines: Well, I don't know. We simply do so. We normally use this in formal correspondence, for example. It's absolutely correct.
I gave in. I surrendered. I doubtfully acknowledged the correctness of the sentence and went on living my life. Until it sank in many years later. I don't remember when and under what circumstances but it suddenly dawned on me. I accepted it and made it part of my active L2 inventory. The thing is that within the slot between not understanding and sinking in I never used the structure because I felt it wasn't safe. Nobody had explained it to me sufficiently; hence I couldn't use it properly.
I remember I had the same feeling of helplessness when I was introduced to may/might/could well. You can try the shop but it may well be closed now. I really struggled to get it right. Sometimes I feel I still use it incorrectly, or rather excessively, and I think I know why... because when I first came across this bit I was enrolled in an English course based on pure communicative language teaching. This meant NO translation. NEVER. Even nowadays I can visualize the room, the coursebooks, and the fantastic NNS teacher/trainer who did her best to teach us some English grammar along with a few basic communicative language teaching principles. Rule number one was, obviously, NO Czech in the lessons. She simply left us to our own devices and I don't doubt she thought she was doing the right thing; she wanted to make us search and explore whenever we struggled with a difficult language point. But for some reason, back then, it was hard for me to find the meaning of a whole chunk in a dictionary (mind you, I didn't know what internet was at that time!). Yes, I could find individual words and their direct translations but longer phrases were tricky.
The story has some implications for my professional life, i.e. professional life of a language teacher. When I think about it now, a little bit of linguistic knowledge on the part of the NS would have been beneficial. Back then, I needed a simple, rational explanation, which, unfortunately, the teacher wasn't able to provide. In the second situation, all I needed was the direct translation and, unlike a NS, the NNS was capable of providing it on the spot. I often think of these two situations when teaching my own English classes. The point is that it's not necessary to stick to the rules of the mainstream/fashionable language teaching at all costs. The priority is our students' needs. It's also good if teachers are willing to go into metalinguistic discussions now and then, especially if they feel it is the only and ultimate option which will help the students to fully grasp a language point.