I have strong opinions about Learning Spanish Through Immersion.
What is Spanish Immersion learning? The basic idea is to surround yourself in a Spanish speaking culture or atmosphere for an extended length of time (more than a two week mission trip) and thus depend on others to help you learn Spanish through conversing naturally with normal amounts of input and output in Spanish. There are different phases of language learning this way - the silent period, the early production, speech emergence (1000 words), then intermediate (6000 words) and advanced fluency.
Many people tout immersion as "the way" to learn Spanish. Well, sometimes!
If the student possesses motivation, a foundation of learning and Spanish vocabulary, and an extended length of consistent time in the language and culture, then yes, it's THE best way. Most of the time it's just not possible for most families to learn with Spanish immersion. Any short term immersion is rather ineffective, other than providing motivation, and good input.
So, what's the answer? In order to be consistent, choose a method you can keep up with. For many, three words a day, a week, a month... whatever you're doing, continue to do it, and increase as you can. Immersion is great, but because it's a difficult goal to attain, we feel forlorn. Even getting a housekeeper, friend, worker, or otherwise to visit with us is not truly immersion. It's providing authentic input which is EXCELLENT. Even the dual language public and charter schools aren't truly immersive. The children are in an English speaking environment 50% of their time (at home) and Spanish and English speaking 50% of their time (at school). If the child isn't motivated, waiting for a speaker of his native language, or a translator is feasible for him.
In short, learning Spanish via immersion WORKS.... with a few tweaks!
However, we simply aren't able to do it, unless we move to a Spanish speaking country, or are fairly continually surrounded by Spanish speakers with no resource for English translation. Programs that say they teach by immersion... well, they don't. They give authentic input, which is awesome. It's important as learners that we know the difference.