Today I came across an interesting article on Overlearning, via Polyglottery, which argues that it’s better to learn a relatively small amount thoroughly than to try to learn as much as possible of a language.
The author’s main point is that some language learners don’t repeat words and phrases enough before moving on to the next ones. This results in them half-knowing quite a lot, but unable to produce what they know smoothly and fluently.
A better way is apparently to repeat things many times, then practice using them with native speakers as frequently as possible. In this way, you are able to produce words and phrases without conscious thought – they just flow out when you need them.
The author also says that you can pick up the grammar by learning how to use words and sentence patterns in various situations. You may not know why a particular inflexion is needed, but you will be able to apply it when necessary.
This makes a lot of sense to me and sounds similar to the Pimsleur method.