Being in charge means that people come to you with questions, problems and suggestions. Having an open door policy creates an inviting and open environment for your employees, but it can also create a non-productive place for you.
Letting people come in and interrupt you at any time, can be a disaster when you are trying to complete a task, or have a deadline looming. Those interrupts often take you into a different thought process and may even take you away from the task at hand completely.
When need to focus on a project, have a deadline requirement or just want to complete something, give yourself permission to close your office door, and work! Your employees will understand and respect the closed door and realize that while the door is closed you are off limits.
Getting into the habit of giving yourself the time and environment to be productive in will benefit you and those around you!
I wish you success!