A recommendation can look like discovery while quietly narrowing the territory available to discover.

Recommendations feel like exploration because each suggestion is new to you. The territory they draw from, though, is being steadily narrowed by your own previous choices, so you experience continuous discovery while the actual range of what could reach you shrinks. Both things are happening at once.

Every so often, get something from outside any system that knows you. A recommendation from a person, a shelf in a library, an old list, a subject picked at random. The point is to reintroduce material that no model of you would have selected.