I'm usually very organized as far as paying bills, but last month I missed one which resulted in a $15 late fee (I called the company and they were kind enough to remove it from my bill as it hadn't happened before). But it made me realize with paying online it's difficult to keep track if you don't have a pile of paper statements to go through.
Another reason I wanted to put cutoff dates and due dates on a chart is that when I make a larger purchase or pay a larger bill (insurance) I prefer to do it right after the cutoff date of the credit card which gives me more time to pay it. I also mark the date it will be paid because on some credit cards/utilities you are able to put in a date closer to the due date for payment.
For bills that are paid annually or bi-annually, I highlight the month due so that I'm aware a payment is expected in that month.
Note: Sort your list by due date.