To be a poet (#3 in a possibly infinite series)

There are many schools and types of poetry. Should a poet pick one and master it?

Pros

1. It gives structure to your practice.
2. Being a master of something is a good feeling and can be good for your reputation.
3. Many of the skills developed by mastering one type, will be portable to other types. (For example, mastering the Shakespearean Sonnet will necessarily teach you a lot about meter and rhyme, which most forms of poetry use).
4. It can be challenging and fun.

Cons

1. It can take 10,000 hours of practice to become a master of something. So you have to really want to!
2. You risk type casting yourself, making it too difficult to break away from the one thing to try others.
3. It can seem like you're just imitating the true masters. Shakespeare was so good at Shakespearean Sonnets, Juan Carlos Williams was so good at imagist poetry that if you pick one of those types to master, you will never be able to hope for being any more than an also ran.
4. What happens if you spend ten years trying to master something and then decide you don't like it that much any more?

My advice: Develop your poetic skills (note the plural. There are quite a few) by learning to write multiple types of poetry well. That by itself can take many years. Then, if there is something in particular you care enough about to devote yourself to completely, go for it. In most cases, you will have developed enough of a style of your own by that time that you won't even have to decide on a particular type. It will just be the way you write.