Embrace closed doors.

"Open door policies" oftentimes result in leaders being, in theory, approachable while in reality they will rarely have more than a few minutes to spare. How can you as a leader change this? Be clear about the fact that you have a busy schedule, but create one or several specific time slots per week during which people can schedule time with you. For example on Fridays between 2 p.m. and 3 p.m. If you are are afraid of wasting an hour a week because no one will seek this opportunity - try it, and if there is really no demand, you better find out why. If everyone is truly happy, there should be positive feedback or constructive comments flowing your way. If the demand is really low, it is easy to make your open office hour a fortnightly event to spread demand, or shorten your hour to 30 minutes. If it turns out that the demand is so high that the hour you scheduled is not enough, this may well be the best investment of your time you can possibly think of because you're getting to the bottom of what drives and slows your company.