Because mental burden costs us energy, we’re evolutionary predisposed to minimize it whenever we can. But in some cases, investing in mental burden can pay off later on, if it’s productive and helps us learn—or, in fancier terms, if it helps our brains develop schemata.
Schema are how our long-term memories store knowledge, and the more we learn, the more complex those schema become, and the more efficient we are at processing them. Someone who is just learning to read, for example, may have to look at each letter and hold it in their working memory before putting words together. Their schema consist of individual letters. Once they get more practice, they are able to take in whole words or even groups of words. Their schema have become more complex, and they are able to process information more efficiently. Reading becomes less mentally taxing.
Investing in helping people develop schema will save them from mental burden later on, freeing their minds to innovate, which is why training and education have such potent economic advantages. Formal education is important but only one of many ways to promote schema formation.