Blogging _ costly hobby for companies

How many of us write blogs only in weekends, holidays and when we are at home? And how many of our blogs are actually written while you are at work? My guess is 80% of your blogs are written while you are at work. I have written all my blogs while I am at work. How much time we typically spend writing a single blog? How many blogs you write in a month? Have you ever tried to calculate the man hours you are spending per month on your favorite hobby and tired to calculate how much does this actually cost your corporate and how much returns you are getting out of your blogs to your company? I am sure we are all good at calculating money.