I'm going to try working on this obsession model next year with my Chinese language learning. I've found it helpful in other areas (including other languages) but I've recently just had too many other priorities to do it well with Chinese. I was recently discussing conscious self-correction with another student recently, it really seems to be key to success in language learning, especially in pronunciation. Unfortunately it's also more difficult to do, as it's uncomfortable to hear your own bad grammar and pronunciation and it's much easier to be understood on a basic level than to get serious about speaking like a native.
One of the reasons this will work so well is that many people aiming to pass a 3-4 year university course or something similar probably won't be putting in anything like the amount of serious, reflective learning that an 'obsessive' learner puts in over a single year. On a smaller scale, even spending a week seriously learning something like juggling will put you ahead of most people who have been doing it on and off for years. You're forcing yourself to build on past development and constantly improve rather than plateau at a much lower level.