Repetition strengthens myelination — the insulating layer around neural pathways. A song heard forty times isn't a song heard forty times; it's the same song laid down in forty slightly different brain states, building robust recall. Children don't ask for repetition because they're stuck.
They're asking because the song is doing exactly what their brain needs. Sing it again. Sing it the way they like it.
The repetition is the lesson..
