Adam Smith was concerned by Mercantilism. This shouldn't be an issue today. His classic model of a pin factory is the basis of today's hyperspecialization.
However, it only takes a few years to a decade to max out specialization. After that, the law of diminishing returns kicks in. One can put infinite effort into expansion of expertise (doing research at the edge of knowledge) for minimal knowledge gains. This has its own rewards. Or one can put effort into a broad knowledge to couple with deep specialized knowledge (the T shape described above). Or one can just go for wide and shallow knowledge.
I agree with Jacob that establishing that deep knowledge is vital to establishing patterns. In that there is a huge mental capacity difference in the people who have achieved expertise in a field, and those that haven't. But there is an equal difference between those who continue to develop expertise, and those who generalize after achieving expertise.
In a scale of personal growth, I would say that shallow knowledge is less than expertise, which is less than extreme expertise, which is less than expertise plus wide general (shallow) knowledge.
From an economic viewpoint, if one can make a higher income than one pays for services, one should maximize this. Following this logic leads to "Boomer results". Those who earn more, work longer, and get more products and services than those who earn less. There are some here who use just this model, higher earning, coupled to higher spending, as they use their time to maximize earnings, and simply save far more than their peers. Adam Smith and I both think this is a fine strategy.
Where Adam Smith and I diverge is that I am considering my personal development as my primary motivator, rather than my net worth, consumption, or productivity.
So for me, learning to drop a tree, and hew it to a beam, saves me $75 (cost of beam, retail) and costs a tree. Economically, this is a loss. The tree is worth more than the beam, and my time must have some value. This is just crazy expensive.
But from this I also get learning, exercise, and a tree out of the way, all of value to me greater than the value of buying a beam, and growing the tree. Or buying the beam, and paying someone to fell the tree, and haul it to the mill, to make the beam, and paying me the value of the log minus felling, processing, and transport both ways.
On a lesser scale, learning to sew a patch can save me buying a new pair of jeans. $13 from Costco, minus cost of patch and thread plus my labor, again, I lose out. And these days I can get them delivered, so I don't even have to factor in a trip to Costco.
But knowing how to both sew and hew, I feel better about me. I get the wider array of topics I can talk about with the confidence of experience, boosting my confidence in social situations. I get a richer variety of crazy disaster stories that can keep people laughing. I get a richer life.
But this richer life comes at the cost of not being able to afford to take 2 cruises a year while working, and a gardener in retirement. It comes at economic cost.
I can pay that price.