is it because strong forms of word are sound clusters?
Hello, Ricefarmer Emotion: smile

I'm not sure I understand your question. According to whom shouldn't the strong forms of words be taught in isolation?
I did study them when I was a university student. I think we need to know both the weak and the strong forms and also when to use them.

What exactly do you mean by sound clusters here, pelase?

Ricefarmer, as miriam said, both strong and weak forms are taught on a need-to-know basis. I think any teacher should teach both forms because they are used in everyday speech. I usually teach these forms whenever a word appears. For example, can. As well as teaching the proper use in grammar, I also teach the two different pronunciations this verb has, depending on the situation in which it is used, by means of examples.
Is this what you wanted to know?