We stop working on projects willingly, or through interruptions. A powerful discipline would be to identify next actions at the moment we cease working on a project, and leave a stake in the ground for the next time. This would immediately seal off the open loop effect. It would probably also be the best time to identify the next action anyway. It would reduce the size of the snowball of open loops to be addressed at the next weekly review.
How successful have you been in developing this discipline?