If you want to develop apps, take your time and make something awesome. Make it fast. Make it beautiful. Make something you’re proud of. Don’t make 60 crappy apps: Make one really good one.
I tend to agree with this article which mostly outlines what David calls "speculative developers" or ones who "barf out as many apps as possible in the shortest time possible in hopes that they strike gold in the App Store lottery".
I disagree with his suggestion of "make one really good one". That's a lot easier said than done and the example he mentions is Marco Arment with Instapaper. It's the equivalent of buying only one stock and not diversifying your portfolio.
For independent developers, I would definitely recommend making something you are proud of first and foremost. Beyond that, focus on building a strong portfolio of applications to diversify your risk. Try and work on having apps in different categories in the App Store and targeting different audiences.
Not many developers can step up to the plate and hit a home run on the first swing. Ship, measure, learn, adapt and repeat.