I don't think you can. The naive answer would be "how many lines of code does the person produce" but I'm sure we'd all disagree with that. I'd say as long as

I don't think you can. The naive answer would be "how many lines of code does the person produce" but I'm sure we'd all disagree with that. I'd say as long as the person doesn't make the same mistake over and over and (maybe) doesn't ask the same question over and over, the person is fine.