Timeboxing is a somewhat overlooked technique in project management. It has been around for decades and seems to go through periods of being fashionable, then unfashionable. This white paper on timeboxing explains what it is, when to use timeboxing, and how to run a timebox.
Uncertainty in project planning is widely recognized in many industries and a wide variety of different tools exists to help optimise the planning process and minimize the associated risks. Read more on the topic of managing uncertainty in projects.