I am aware of ego depletion. What am I not convinced of is that general work, in any area, will increase the time it takes prior to ego depletion. Could you perhaps point me in the direction of any appropriate research?

Furthermore, if this were true, why would it only apply to what you termed 'productive' and not 'consumptive' work? Would studying for a class not apply to this rationale? If not, why not? If so, wouldn't reading Less Wrong also help extend the 'time to ego-depletion'?