How many drafts is enough?

As you know the WIP is now Ws IP! Two volumes: one ~240k and one ~200k words, but at least I feel like I'm getting somewhere now! During a recent discussion with a writing buddy I wondered how many drafts I'd gone through - now that 'the end' is in sight (my sis tells me too many and to get them out there!), but an article in the December issue of Writing magazine with writer and publisher Stewart Ferris says that is one of the commonest mistakes writers make - sending their pride and joy out into the world way too soon! He says that it shouldn't leave the nest until Draft 10! He lists what each draft is for: tightening the structure; character development; improving the dialogue; language and imagery; restructuring; adding conflict; improving the crucial opening pages; more character development and final proofreading! It confirms what I have found in my journey - that I can only concentrate on one or two aspects as I rework the novels - oh and that's another thing - there aren't writers - only rewriters which is what I feel like at the moment!