With that attitude, I'll finish life way before you!

I doubt this comment will get far on this forum, but it does jog my memory of my favorite professor and mentor in college (a very long story). Anyway, I was complaining to him that I was struggling with keeping up learning something in fluid mechanics, and he pointed out that it took Bernoulli 20 years to put together his general equation, but, as students, we’re expected to master it in a weekend. Anyway anyway, life isn’t a race, unless you’re trying to get ahead of someone else. To your point, plenty of people can do wonderful things in their own time and on their own pace, and that may not be as fast as someone else.

I had a different takeaway. That you can fast-track the pointless "traffic jams" (using the race analogy). Why sit in traffic for no reason?

In his example, he tested out of classes that he was already proficient in—not all classes. Doing this occasionally would allow you to have more time for things that matter.

Well, it's more like - if you can afford 1:1 instruction and find a teacher whose style really fits you, you can really speed up your learning.

I've experienced this with guitar. Self-study can be done but you really need a coach who can push you further than you think you're ready to go, along with tailored instruction. You'll make years worth of progress in months this way.

There are often compounding benefits to moving quickly.