Because you can't Optimize for discretionary timeOptimize for discretionary time
Because time is all we have.
without doing so.
Because you should Seek flow statesSeek flow states
All emotional anguish and mental quandaries disappear when you enter a flow state. Put another way: the only problems you have are the problems that prevent you from entering flow.
It helps to P..., but working long hours inevitably means spending lots of time not in flow.