One thing is certain, most English courses in Brazil offer a minimum hourly load.
Well, at least most nightly courses have a weekly workload of 6 hours divided into three classes of two hours (every class). Not much, by any standard.
So, to the guys that are going to nightly courses, be aware of that, and please train train and train your English elsewhere. Read newspapers online, take a work book/ a grammar book and grab some novel or any other fiction, speak to a classmate, what you have. Do your listening, take a CD, watch cable TV, immerse yourself.
If possible get a good teacher, invest time and money into your education, it is a bit expensive, but remember that ignorance is even more expensive.
Grab any spare time you get, to read, listen, or participate in all things English.
Be curious (in a healthy way, you know, curiosity killed the cat...but damn it! the cat had seven lives anyway! Well the cat that learn English have nine!
When studying in a course, don´t get home and throw the books gathering dust someplace. Do your homework, do it as soon as possible, then have fun, read Dilbert, watch some TV show, listen some radio (in English).
Then you will see that effort makes wonders to your learning, it worth the sweat.
I must admit I am talking about that the (only) course I took some time ago, I don´t want generalize, but it wasn´t that hard. Well, not to me.
Even so, it didn´t cover all the topics to a basic level, still many of my classmates lagged behind.
I usually went late, and many times we had some exercise on the book, some two or three pages.
Everyone was focused into doing it, the silence was so dense that you could cut it with a knife, some of them were clueless, others progressed slowly in the task...
I did my bit, and before the first half of the class ended, I had it finished up. It was then that I helped some out, or I cleared my doubts, many of them having little to do the textbook...things like ''what the pronounce of "eat" and "ate" or the difference of pronounce within "three/tree" or something else fished on the Internet!
Moral: one have to get a good teacher, but one have to be equally a dedicated student. And that begins outside the walls of the course building.