The modern communication tools aren't designed to save productivity. People like things with instant response, so things like commenting on Hacker News or sendi

The modern communication tools aren't designed to save productivity. People like things with instant response, so things like commenting on Hacker News or sending a email works instantly, but there is no mechanism for things like telling you that the recipient is busy at the moment and will be available at 4:00 PM when he would start reading the email. Productivity isn't just about cutting down the amount of time needed for a single job, it's about arranging for things to be done more efficiently.