Many coaches instruct their clients that the best way to be good at something is to practice it over and over again. It is thought that narrow repetition of a specific move, skill, or technique will lead to mastery. However, it seems there is a better approach that will generate lasting benefit.
In an article on Scott H, Young’s web site, he points to recent research that supports the idea that variability is even more important than straight repetition. This is due to the idea of contextual interference. Young explains:
Contextual interference occurs when you practice the same skill, but vary the situations in which it is called for.
For instance, you could practice your tennis backhand by being served backhand shots repeatedly. Alternatively, your coach could mix things up: serve you backhand shots interspersed with balls that require a forehand shot.
Or imagine preparing for a calculus exam: you could study all the questions that require the chain rule, then all the questions that use the quotient rule. Instead, you might shuffle these questions together so you can’t be sure which technique is needed.

Young goes on to point out why contextual interference improves mastery. One of the reasons is:
Identifying problems correctly and ensuring the correct technique is associated with the problem. A major difficulty in learning isn’t getting knowledge into your head—but getting it out at the right time. Practice that repeats the same technique in narrow situations may result in skills that aren’t accessible when you need them.
Learn more about the advantages of variability in your training by reading the rest of the article.