A few hours a year ...

Descartes apparently said that one could only 'do' metaphysics for a few hours a year. What do we make, then, of our current academic philosophers, who 'do' philosophy for many hours every single day? Are they simply heroically strong, mentally speaking, in a way Descartes could not have comprehended? Or did Descartes mean something else by metaphysics, something so mentally debilitating that we have quietly sidelined in it modern intellectual discourse for fear of sapping our energies? Have we substituted some elaborate metaphorical sudoku game for the strenuous, enervating practice of genuine metaphysics?