Can some experienced NCO's help me out here?

Is it true that once you get to a certain rank, the military begins to make you take college courses such as algebra (traditional academic college courses) in order to be promoted. I've even heard that for people to reach E-4, they are often forced to take academic college courses and earn a degree to be promoted. Is this true or can people go through their careers without having to take these traditional academic college courses? Are there senior NCO's without college experience?