With English, I only learned basic/intermediate "grammar" in a language school. All I remember from those classes is that the parallels between English and Spanish were striking, but my teachers never pointed this out to me. After those 3 intensive 2-month courses, the rest was just input, input, input and more input: Music, movies, books and the web. I did lots of transcription with Pink Floyd songs and memorized almost their whole catalogue.
With Mandarin Chinese, I only took a 60-hour course in a language school and then forgot almost all of it. I just could not understand my teacher and the grammar book was Greek to me. I also could not fathom why she insisted in teaching me the names of fruits and the verb for "to throw water" instead of more immediately useful words. So when I came back to the language 2 years later, I gave the books away and decided instead to attend Christian meetings in Mandarin, talk to teachers through italki and create customized word frequency lists based on my reading materials, using text analysis software. I haven't touched a grammar book since that first failed attempt, and yet I passed HSK 5 last year and I'm now conversational in the language. Word frequency lists and the fact that I memorized 3,000 hanzi in 6 months have been crucial to turn any input into "comprehensible input".
As a teacher, I only touch on "grammar" (aka "patterns") when correcting essays or when the student has a specific question, because that's when he's ready for it.


