Myth #1: Editorial calendars are static. Once they are set by the publisher for the year, they never change.
Reality: Not even close. Ed cals change all the time. That means opportunities which look promising for a client one week may not be around the next. If you are stuck with the ed cal monitoring task, you will have to conduct twice the amount of follow-up with the reporter or editor in question to determine what the publication is really planning as far as editorial coverage for a given issue.
I am sorry to say I believed this.