Your suspicion is probably true, but the example in the essay was considering wasted time akin to poorly invested money. Losing a day to email/HN is like losing a few dollars on a horse race compared to sinking half your fortune into a diamond mine in Zaire. Obviously, those losses per day add up, but I think its probably just as wise to learn how to watch out for the large time investments that are going to simply absorb resource without return yield.