It’s funny… I didn’t think I would attract so many new users to this post. I guess I should have considering the provocative nature of the title.
One thing I would say to you Harry is that you shouldn’t necessarily just switch full out to studying books and stop building sites. I for one started off just doing the administration and theming (and I didn’t buy a book for a long time). The theming part of Drupal takes quite a bit of learning, but at the same time it provides a structure that will work even while your skills are developing. That is to say, you won’t necessarily be able to do everything you want to do when you are starting out, but if you meet those challenges on the field, and stubbornly push forward, the book knowledge will become much more relevant.
My standpoint is that the best way to learn is to start building a site on your own, but with a set of books by your side. Then as you encounter issues start looking for the answers in the text and online. Much of what you have to learn isn’t written out clearly in any book that I have found yet. A lot of it has to do with recognizing patterns and troubleshooting odd issues that come up when trying to make a site look and act how you intend it to.
You should expect many hours of frustration and confusion… these are the dues we pay to own the skills, but if you get it down it can be a very lucrative career (or money saving hobby). My honest opinion is that from Newbie to master developer there are about 1 – 2 years of struggle (unless you are already coming from a programming background).