No matter how well written and comprehensive your programme schedule is, there is a strong likelihood the project will not be delivered on time.  Why is that?  Because every project is subject to uncertainty.

Unfortunately, even when the original estimates are good, and actual task durations are on average close to the original estimates, a phenomenon called merge bias means that the more predecessors any given activity has, the less probable it is to start on time.

Because we recognise and acknowledge this risk, every programme we write undergoes as a matter of course, an in-depth risk analysis using Monte Carlo simulation.