Audio version
Whether it’s learning how to play the oboe, hit a backhand slice, or type (with all of your fingers, not just your thumbs ), one of the most common ways to set practice goals is in units of time, or a certain number of repetitions.

Play the exposition of this piece 5 times. Practice scales in these three keys, with their associated arpeggios for 30 minutes.

On the surface, both seem pretty similar. But are they really?

Let’s say you had to pick one method for structuring your practice for the week. Or for assigning practice tasks for a student.

Which do you think might lead to better quality practice and learning gains in the week ahead?

Suture training

A study in The American Journal of Surgery sheds some light on which approach might be best.

Thirty first and second-year medical students were tasked with learning a surgical knot-tying procedure1 (check it out here if you’re curious – and it’s a simulation, so no worries if you’re squeamish).

They all started out by watching a video of the procedure, and were given 10 minutes to give it a try without any instruction or guidance, which established a baseline level of performance (the pre-test).

The students were randomly assigned to a group, each of which had a slightly different criteria for completion.

  1. The time group was instructed to practice for 90 minutes.
  2. The repetition group was instructed to complete 12 repetitions.
  3. And then there was a third group – a proficiency group – which was told to practice until they could perform the procedure at a certain level of proficiency. Which for this task, meant a) completing the procedure within 3 minutes, b) placing the stitch within 1mm of the marked target, and c) tying a secure knot – two times in a row.

Then, each student performed the task one last time, to see how much improvement they made over the course of their practice session (the post-test).

Differences in practice gains

All three groups improved from the baseline test to their final test, but one group improved significantly more than the others, in the same amount of time.

The time group demonstrated an average improvement of 394.49 points from pre-test to post-test (70.51 to 4652).

And the repetition group improved by 316.6 points (150.2 to 466.8).

But the proficiency group improved by 496.1 points (47.6 to 543.7) – a much bigger increase in performance than the other two groups.

Uniformity of performance

In addition, the standard deviation of the students’ scores in the proficiency group was much lower than that of the other groups (47.89 vs. 125.72 for the time group, and 111.10 for the proficiency group). Which is a fancy way of saying that everyone’s final performances in the proficiency group were much more even, despite performing at very different levels in the initial practice attempt.

So it’s like everyone in the proficiency group got to a pretty similar high level of performance, whereas in the other groups, some students got to a high level, other students struggled and performed poorly, and some were in the middle. In other words, there was a lot more variation in the final performance scores of the students in the time and repetition groups.

But wait! What about…?

Of course, this would only be a fair comparison if the three groups spent about the same amount of time and completed a similar number of repetitions in their practice session, right? Fortunately, all three groups’ practice metrics were pretty much the same3.

  • Time group: 90min; 10.6 practice repetitions
  • Repetition group: 98.6min; 12 practice repetitions
  • Proficiency group: 88.7 min; 11.9 practice repetitions

Take action

It’s really easy – and tempting – to prescribe practice in units of time. Or as a set number of repetitions. But as it turns out, neither are especially good ways to approach practicing in most cases.

After all, if you pick up on something quickly, you might get bored before the time or repetitions are up and end up practicing mindlessly. Or conversely, when you’re working on something challenging, a set amount of time or number of repetitions may not be enough to get done what you need to.

Proficiency goals, on the other hand, are much more conducive to deliberate practice, and encourage more engaged, thoughtful practice. But the challenge is…how do you know when it’s good enough to stop practicing? Because, honestly, does anything ever sound good enough?

The authors describe a process for establishing a set of “mastery criteria” that might work with music too. Essentially it involves observing experts performing a task, analyzing the task, and then identifying the most important aspects of the task that are indicators of a high-level of performance.

In music, this might involve quality of sound, intonation, and rhythm for starters. And then more high-level, yet integral aspects of musical performance, like phrasing, character, and so on.

Ultimately, there are a ton of criteria could be used as proficiency measures. But using them all could be a bit paralyzing. So I think the idea is to pick just a few to aim for. Get those down, and then continue to refine and identify increasingly challenging criteria over time.

I know…still easier said than done, and it makes my head hurt a little bit just thinking about how to establish mastery criteria with my daughter on Monday. But then again, this sort of thinking, reflection, and experimentation is part of the fun of it all, no?


  1. laparoscopic intracorporeal suturing, to be specific
  2. The score is essentially a combination of their time/accuracy/knot security scores
  3. Not a coincidence, of course. Based on a previous study, the researchers knew that the three groups would end up coming pretty close.