The idea of "implicit learning" (p.66) is very intriguing (acquisition of linguistic patterns without explicit attention or instruction). I definitely did not learn my second language in high school this way. Let me rephrase that, I DID LEARN French in h.s. not in this way, nor did I acquire French. I learned what I needed to to pass the test through drills, very structure games, and forced output. I was unable to put anything together in a meaningful way when put on the spot.
In college I studied abroad in France, lived with a family and after a few months began thinking and dreaming in French. When I spoke on the phone with my family in the USA I would trip over words and have to really work at my English. Dekeyser concluded in a study that "...there may very well be no exceptions to the age effect...everybody loses the mental equipment required for the implicit induction of the abstract patterns underlying a human language." Dare I disagree? As I stated earlier, I really had to work at retrieving English in my brain. Grammar, definitions of words I didn't know and every aspect of my life was in French. There was constant "meaningful learning".
I may not have understood every word, but I feel part of non-native fluency is being able to ask a question in the SL, have it answered in the SL, and understand it.
I taught middle and high school for 3 years using the method of drills, forced output, etc. The last 3 years I used TPRS, lots of meaningful, comprehensible input, no forced speech, & low affective filter. Classrooms were quiet for about a month and there was very little writing. It didn't take long and students were speaking on impulse and writing like mad. I loved the timed writings, 5 minutes, here is the topic, I will not grade you on accuracy or content, the only rule is shoot for 100 words. My students who began this method with me from the start would write up to 150 words or more in 5 minutes. My level 3's struggled more, they had been used to the drill, forced speech method, they were worried about correctness and took awhile to get over that. They too eventually came around. I really saw first hand what works and what doesn't IMHO.