It's never so simple as "comment more" or "comment less". Some things are best explained by identifiers, and needing to comment them is a sign of poor code. On the other hand, some code requires domain-specific knowledge to understand why it does what it does, and as much of that knowledge as possible should be spelled out (or at least cited) in comments. I have written modules where no comments were needed anywhere. On the other hand, I have written modules where every line required a paragraph, a figure, and a short proof. The best guideline is that comments should say as much as it's possible to say without going off topic or repeating things that are obvious from the code.