Interleaved practice

Here’s something most of us have experienced: you take a difficult passage, practise it 15 times in a row, and by the end it feels solid. The next day, the progress is gone. Your time feels wasted.

What happened? You were drilling the passage in what researchers call a blocked schedule — repeating the same thing over and over before moving on. Blocked practice is so common it’s our default: it’s how most school drills work, and it’s what cramming looks like. It feels productive because each repetition is easier than the last.

But that ease is the problem. After two or three repetitions, the passage is sitting in your working memory — a very short-term mental buffer that holds about seven items at a time (Miller, 1956). You’re no longer retrieving the passage from long-term memory; you’re just replaying what’s already in your short-term awareness. And since performance requires long-term recall, you haven’t actually practised the skill you need.

In 1956, cognitive psychologist George Miller published one of the most cited papers in the field: “The Magical Number Seven, Plus or Minus Two.” He showed that humans can hold roughly seven items in working memory at any given time.

This matters for practice because anything that’s still in working memory doesn’t need to be fetched from long-term storage. If you’ve just played a passage, playing it again immediately is trivial — the motor plan and musical information are still “loaded.” You need to clear that buffer before the next repetition will actually build durable memory.

Try the demo below. You’ll see seven items, then answer a question about them. If you answer immediately, it’s easy — the items are still in working memory. If you had to answer a day from now, you’d need real long-term recall.

Interleaved practice (sometimes called “mixed” practice) is the alternative. Instead of repeating passage A twenty times, then passage B twenty times, you alternate: A, B, C, B, A, C, and so on. Each time you come back to a passage, it has been pushed out of working memory by other material, so you’re genuinely retrieving it from long-term storage.

The research on this is striking. Rohrer and Taylor (2007) had students practise maths problems either in blocked or mixed order. During practice, the blocked group performed better. But on a test one week later, the mixed group scored vastly higher. The same pattern appears in motor-skill studies, including work with musicians (Stambaugh, 2009).

The reason interleaving works is twofold. First, it forces genuine retrieval, which strengthens memory. Second, it practises discrimination — figuring out which approach or fingering to use, rather than just repeating the one you just used. In a real performance, you don’t know in advance which skill is needed next. Mixed practice trains that decision-making.

Divide your piece into small passages — small enough that a few minutes of focused work produces visible improvement. Then, instead of spending 15 minutes on one passage, rotate through several in short bursts (two to four minutes each). Come back to earlier passages after working on others. Randomise the order when possible.

This will feel harder. That’s normal, and it’s the point. The effort of retrieving a passage after a short break is exactly what builds durable memory. The mild discomfort during practice translates into significantly stronger recall on stage.