When you’re implementing a bad plan yourself, instead of having a mentor bail you out by fixing it, a few really useful things happen:

• You learn many more details about why it was a bad idea. If someone else tells you your plan is bad, they’ll probably list the top two or three reasons. By actually following through, you’ll also get to learn reasons

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Because the stakes are higher and it takes longer to see the results, all these decisions require what I’d call conviction : the confidence that your idea is good enough that it’s worth throwing a lot of effort behind.

Overall, I probably did a pretty bad job. But, importantly, I was able to see my mistakes play out in the real world. Instead of modeling what other people would tell me to do, I built a model of the problem directly. So when I got negative feedback, it wasn’t “Mentor X thinks this plan is bad” but “the world works differently than you expected.”