If a transportation or labor economist wants to determine the value of someone's time, they typically use that person's wage. An average day for The Perfect Substitute (TPS) gathers about 120 hits (and 200 viewings). However, weekends are about 60% lower than weekdays. Thus the following transitivity property must hold for a minute of the average TPS readers' time on the margin:
weekend minute > TPS minute > work minute
Perhaps reading TPS is always shirking, and it is just that monitoring is more effective at home than at work. That would be true for me, anyway.