My study in Switzerland was pretty intense. Class began at about 8:30 every morning and went until 1. There was une brève pause from 10 to 10:30. I was still working on east coast time, so my studies began at about 3 in the morning and finished around 7. Much to my tutor's amusement, I spent the first half of class just trying to get my head in the game. I would have an exercise, know the answer, and take two minutes to actually bring it out. In the afternoons there was often some sort extracurricular activity. I went out to a vineyard on Wednesday in the small town of Aigle. Best wine in the world.
What I picked up from my study is what I already knew--acquiring a new language is hard, and people who claim that you can do so inside of a year without changing anything else about your life probably have their hand in your pocket. It isn't to say that no one can do it. But if you're going to learn a new language you should expect a fight and gird yourself accordingly. You should even expect it to be hard if it's your child.
My tutor here in the States learned French when she was six at an immersion school. Her recollections of picking up French are bracing: long periods of not knowing and knowing you don't know; French teachers yelling at you for doing something wrong, and you not being sure what it was. My son has just started his French studies (his request, not mine) and they're going to intensify over the summer, so I expect him to get a little bit of the same. It's obviously true that it's easier to acquire language when you're younger. But this has no meaning to the individual experiencing it--your only frame of reference is your own skin.
Accordingly, I had a French session yesterday and picked up the intensity. Two hours, instead of the usual hour. All of it in French. If I didn't understand something my tutor was trying to explain, oh well. C'est Français. By the end, my brain was cake batter. Language really is different that other intellectual pursuits in its physicality. Learning to properly pronounce "Vevey" isn't a matter of abstract theory--it's a matter of training your mouth and tongue, in the same way a ballerina or singer trains, in the same way one would master a jump shot. There's just no way to make that go quicker. Hours must be put in. Reps must be performed. There's no other way.
In many ways I compare it to my journey of becoming a healthy person. The same get-rich-quick claims revolve around language-learning, as around weight loss. But I found that becoming a healthier person meant acting, thinking and making the kind of decisions that a healthier person would. It was not enough to say that I wanted to lose 20 pounds, any more than it would be enough to say I want to speak French. In both cases, I have had to learn to think like the man I wanted to be. Your old self can't come with you. In both cases I found that I what I doing was more important than what I consider myself to be. Words like "intelligence" and "discipline" held no power for me. Words like "practice" and "planning" did.
I don't say this to ward anyone away from a foreign language, or from French specifically. On the contrary, there's a beautiful democracy to it all. I am not convinced that anyone can be a Baudelaire. But I am convinced that anyone can understand, and make themselves understood. It's just that the work is unrelenting. It's a law of nature. There's no way around it.