Over the last few years the yoga industry has been openly discussing what level of training is sufficient to become a teacher of yoga.
We often look to our governing bodies to help with these questions, but I believe that this is a question most yoga teachers should be able to answer for you.
200 hour courses are simply an introduction to yoga instructing. If you are a self-motivated learner then these courses could very well suit you but you go in with your eyes open.
A 200 hour short course will set you up with the basic skills of instruction for a standard class. When you graduate you then will be ready to start working towards an entry level of teaching. According to Yoga Australia, to gain Level 1 teaching status you are required to have completed 350 hours of teacher training and have been teaching yoga classes for a minimum of 12 months. This means that even though you have completed your 200 hours you will need to seek out another course or often expensive mentoring programs to bring you up to the basic entry level of teaching.
But for many of us, the thought of going out on our own at this fledging stage, to stand up and teach a group of people, is enough to make you give up before you have even started. If this is you then you will want a course that will guide you through the learning process and give you the teaching and class content you need to teach on a regular basis (a beginners class is simply not enough).
Summary: If you cannot register as a teacher before 12 months, then it makes sense that a teacher training course should be 12 months in duration and preferably with a registered training organisation to ensure a professional standard of training for you.