An acquaintance suggested the opposite approach to what I suggested yesterday: spend little time on the subjects that you like and are good at, and focus on the more challenging ones. The premise of this approach is that it optimizes your grades. You'll probably get good grades on the subjects you like anyway but unless you work hard, you won't get good grades on those you don't. We discussed this today.
The boys agreed the approach probably optimizes grades, and Paco mentioned that this is indeed what he does: spend a lot more time in French than in Math. But we found two problems with the approach.
1) It might optimize for "results", but it doesn't for personal "fulfillment". Ideally we should spend as much time as possible on the things that we enjoy the most. So I guess this is something to balance: results vs. fulfillment. Sometimes the two are aligned, other times they aren't.
2) GPA is important, but doing something extraordinary can be even more important. Say you like science and struggle with French. You do little work on science and still get an A. You work hard on French and get a B+. But what if you work a ton on science, do an amazing science fair project that wins the state championship, still get an A, work less on French and get a C. Winning the state science fair competition might more than make up for that C you got in French. It is probably a personal thing: some people tend to be more "well-rounded" while others tend to stand-out in one thing...