The pattern calls for super bulky yarn? He decides to use three strands of sock weight yarn.
Those three strands held together look a bit thin? Oh, that's OK, he says. I'll use a big hook, and it'll be lacy.
I was dubious, of course.
A few days later, he showed up with the cutest hat, which could only be called The Littlest Hiro. It was 16 inches around, instead of the usual 20-ish.
It was very stretchy. It could fit a kid, and it could fit me, with my size Medium noggin, edging toward Large.
The crochet gods had rewarded him yet again.
I think the lesson I learned from him is: Why not?
Why not be more fearless in yarn choice? In pushing the gauge where it has not gone before? Why not pick a yarn you love and make the pattern conform to IT, rather than the other way around?
The results could be fabulous, or, at the very least, pretty darn cute.