In other words: if a CR question asks only for performance feedback, or only for OOP structure feedback, etc., is that valid? And would answers providing review feedback on other aspects of the code be off-topic?
For example, Time and space complexity of base conversion code . Is it possible to constrain this question only to algorithmic feedback?
Questions can certainly request specific insights areas of focus. But that does not mean that other areas have to be ignored.
If you have insights or observations in to other areas that were not specifically requested, then you are free to answer on those other issues.
Obviously, your feedback may not be as valuable to the question asker as they may want, and they will likely accept a different answer that covers their most significant concerns.
Part of the basic premise of Code Review as a site, is that any and all feedback is, or should be welcome. See the help center "On topic" page for that:
Do I want feedback about any or all facets of the code?
Feel free to call attention to specific areas you are concerned about (performance, formatting, etc). However, any aspect of the code posted is fair game for feedback and criticism.
