With the way I write I wouldn't use the term drafts. I work on one poem at a time and keep at it until it feels right to me. It's a continual process. Sometimes, though, I will revisit a poem a month or so later and tweak it a little after gaining a bit of the objectivity that is gained from being away from it.
Poetry is different from any other thing that I write, in most cases, poetry is something that wells up from inside of me and takes on a life of it's own. I usually write a poem in one sitting, and in most cases it is polished in one or two drafts. In some cases, such as the poem I wrote following my father's passing about my parents being reunited in heaven, the first draft was the only draft. However, a poem that I wrote about my mother's passing, had to many drafts to count, as it took me thirty-two years to complete before I finally felt that I had captured the essence of the picture in my head. I always keep all the drafts of any poem that I am working on, so that I can go back and look at it for inspiration or perspective.