[jeffreyrogers]

I get what you're saying, but people learn the math in 4-6 years or so, so while it's definitely a lot of work (not that many other things that people spend that much time learning), it's also fairly well bounded. You know that if you study hard for long enough you'll know most of what you need to know, and then the parts you don't know yet, you have enough awareness of to know when you need to learn more about them.