The fact is that the most productive managers DO NOT have an open door policy, and this with good reason. When taken to its extreme, managers think that they should be available to interruptions as long as there is no-one in their office. The impact of this unconscious decision is that a manager never creates a space in which they can be deeply productive, unless they come in early, stay late or come in on weekends.
I say to managers that they need to schedule their times to have an Open Door, and allow themselves to be interrupted only when there are emergencies. This takes careful scheduling, plus an effort to notify others about the exact nature of this “modified” open door policy.
The result, however, is more quality time for both the employee and the manager. The manager is able to give 100% of his attention to the times when he has to do uninterrupted deep thinking, and the times when he has the employee in front of him in need of his attention, without his mind straying to other activities. The employee gains by being able to gain the full attention of the manager.
A modified open door policy is a win-win for everyone.