There are lots of opinions on what makes well-commented code; we can't really define absolute universal rules. But I have found some guidelines are quite useful:
✅ - Code without comments is suboptimal.
✅ - Too many comments (one per line, for example) is probably a sign of poorly written code.
✅ - Comments should explain why, not what. They can optionally explain how if that's particularly confusing.
Any other guideline that we should consider when documenting code?