Discovery should have a point of view
A large feed is not necessarily a useful feed. Good discovery reduces the work of finding worthwhile material while still making the basis for selection understandable.
Look for topic structure
Topics, themes, and collections help a reader move beyond isolated links. They make it possible to follow a question over time and notice connections between fields.
Check whether the app supports attention
Useful signals include readable pages, clear progress, a calm interface, and controls that help you return to something later. The product should make reading easier, not turn it into another engagement contest.
Use recommendations as a starting point
No system can decide what is valuable for every reader. The best app gives you strong starting points, then leaves room for your own judgment and curiosity.