Yeah, you definitely should only submit the best possible code in 8 kyu katas, or else all your future employers will see them and find out how bad of a programmer you are.

I think you read test results wrong. The first test passes, and it's marked ggreen. The -10 you see comes from the second test, which is enough(100, 60, 50).

• What criteria you use to determine when flexing is great?
• What makes this code not meet those criteria?
• What alternative do you suggest?

I don't agree. It's not best practice (despite the votes), but it's certainly not 'very bad' either. It's arguable if it's even 'bad', really, in this case.