This is the exact amount of failure you need to thrive and make progress.

This formula can help you make progress without stagnating - and it's based on not succeeding all the time.

Productive learning happens when there’s a mix of challenge and a feeling of accomplishment, though sometimes it can be hard to tailor conditions to reach a perfect balance.

As it turns out, it may be better to not succeed as much.

A 2019 study argues the optimal circumstance for progress is when you are failing 15% of the time.  

“In many situations we find that there is a sweet spot in which training is neither too easy nor too hard, and where learning progresses most quickly,” authors led by Robert C. Wilson wrote. 

“For all of these stochastic gradient-descent based learning algorithms, we find that the optimal error rate for training is around 15.87% or, conversely, that the optimal training accuracy is about 85%.”

In short, the authors concluded that you need some shortcomings — but not too many — in order to make progress over time. The blend of success and failure can teach us what works and what doesn’t, without taking too heavy a toll on our confidence.

“We show theoretically that training at this optimal difficulty can lead to exponential improvements in the rate of learning,” the researchers wrote, adding that their findings suggest training at a fixed difficulty may not be entirely effective. 

The findings make sense intuitively, too. Consider piano lessons — you would quickly stagnate if you played “Twinkle Twinkle Little Star” over and over again, without moving on to a more complex song. 

The study noted that so-called staircasing procedures, or tasks that are incrementally modified to be more challenging, are typically designed to produce an 80% to 85% rate of success. 

“Similarly, when given a free choice about the difficulty of task they can perform, participants will spontaneously choose tasks of intermediate difficulty levels as they learn,” the researchers wrote.

But using this framework, you can modulate the difficulty of the tasks you do so that you are incorrect or mistaken a little less than one in five attempts. Failing at about a 15% clip, according to the study, can help maximize your growth and competency.

The idea is similar to Leo Vygotsky’s zone of proximal development, which says we must attempt tasks that are slightly above our current abilities in order to reach that next higher level. 

Apply the 85% Rule

It’s no secret that menial tasks make people bored, and that too much complexity can be discouraging. Both extremes can cause people to give up. 

Try to think of one specific project, and break it down into the two or three skills that it’s made of. 

For my own writing habits, for example, I started writing one blog article per week in 2018. One article was not much, but it was much higher than zero. 

Once I became accustomed to that rate of work, I bumped it up to two. 

Then eventually, as my writing improved and my speed ticked up, I reached five to seven articles per week.

What skills are you aiming to develop right now? What side projects would you like to see improved upon? 

If you can break down those projects or skills into tests or tasks, arrange them so you can fail or make a mistake about 15% of the time (and thus succeed 85% of the time). 

Once you establish your sweet spot of failure, then your success rate, confidence, and skill will rise.