All of the time. But they don't just hire out muscle. Since they are a paramilitary and covert (undercover) team working for the Byzantine government they often work in cooperation with other units, hire on assistance (though not necessarily disclosing what they are really up to), and collaborate with various experts on different assignments, missions, or adventures. They take on local guides, men-at-arms, work with the "police," with the military, with government officials, have even done cooperative missions with semi-autonomous enemy forces.
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Better to succeed with the help of others than to fail alone in your hubris.