There is no limit to it in principle.
Labor becomes a commodity, subject to supply-demand law.
Rational planning as one sort of specialization that is not efficient. Much of the power resides in the implicit computations of distributed economic decision-making. It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard of their own interest. We address ourselves not to their humanity, but to their self-love, and never talk to them of our own necessities, but of their advantage. Marx, Darwin, Wagner, Nietzsche, Dickens, Zola, et al.