Naturally, in a large volume of normal conversation, the most common words are going to repeat most frequently (see Zipf’s law). Therefore, getting a lot of inp

Naturally, in a large volume of normal conversation, the most common words are going to repeat most frequently (see Zipf’s law). Therefore, getting a lot of input is still (a form of) spaced repetition, just not a conscious one. In fact, it has been hypothesized (Krashen’s input hypothesis) that adults also acquire language subconsciously through input. We just spend less time on it than children.