It would be more preferable to get (e.g.) 12 degrees in a year and be done with it. Online schooling that has you take tests and gives you the degrees would be far and away more rewarding than getting hammered by years of invested time and a large debt.
Unless you're the kind of personality that enjoys academia, don't bother.
Online tests are a good way to maintain or solidify knowledge, but university degrees are definitely more rewarding for most people
The most rewarding aspect of university study is the exposure to intelligent, educated people who are working on awesome projects. While I personally disliked many aspects of academia, the value of this community is hard to over state and it doesn't exist when you are taking online courses from your own home.
I definitely don't believe people should leave work and go back to university in any but the most exceptional cases, however. If I were to take three years off for further study it would cost over $300,000 in lost income and course fees alone, and I don't even make that much compared to many HN readers.
Unless you're the kind of personality that enjoys academia, don't bother.