[RickOShay]

Well that is hard to say, cuz I kind of took a leisurely pace with learning, after I had done with my two years of study in college. So I really don't know.
I think anybody who truly kept at it though could have 2000 down in 3-5 years.

But your average person who has a life etc, would probably need 5 or more.

In any case you will find that lots of similarly looking kanji start to have the same readings, so it kind of helps. I should say though I never bothered learning individual kanji, my approach was to learn new vocabulary words and always learn how to read their kanji at the same time.