deliberate practice

In a nutshell:

An expert breaks down the skills that are required to be expert and focuses on improving those skill during practice or day-to-day activities, often paired with immediate coaching feedback.

Another important feature of deliberate practice lies in continually practising a skill at more challenging levels with the intention of mastering it.

What educational researchers say

Some say that anyone can become an expert with deliberate practice, others say that some skill level is also required ...

SRS Learning says

... we aren't trying to ensure low attaining maths learners are become maths experts - merely that learners increase their attainment -  if we can use some of what makes experts expert to do this - why not?