How does one measure the rate of self-learning? Learning fast at your own pace is great, but by what standard do we measure "fast"?

even if we do somehow find a way to measure "progress of learning," how do we define if we are learning fast enough? One the big reasons I prefer self-learning over dropping loads of money into an educational institute is that I don't have to conform to their rate of teaching/learning. But then at what "speed" of learning, can we justify that what we are doing is better than learning at a university?