G. Mark’s Answer
As an engineer, the "required" amount of schooling is generally a bachelors degree. I assume many engineers have an associates degree. However, the position I was hired at required a masters or doctorate. One thing you need to know about most technical fields, however, is that there is no such thing as "enough" education, not only because there's so much to learn, but because you're talking about a moving target.
If you look at folks who are happy and successful in their careers, you'll generally see someone who just can't get enough of it. If you look at anyone in a technical field, they talk, think and listen to anything involved with it, so learning is more or less not only effortless, but irresistible. You think of someone being retired sometimes as thinking, "Whew -- glad that's over. Now I can forget about that stuff." Not a chance. Watch an engineer's face when they see a TV commercial for some new technology and see their eyes go wide. See them attend a movie and they'll leave and talk about how the special effects must have been done and how much computing power they must have needed or criticize the the silly and impractical design of something they saw.
So the answer to how much schooling is typically required for most careers, and the answer is generally, "more".