planning, leeway materializes between an activity and its benchmark anytime the relevant planned date of the activity preceding the benchmark is earlier than the benchmark date. This may appeal to Lean Construction proponents and those aware that the CPM concept of total float should attach a disclaimer: scheduler beware! With some exceptions  , few practitioners are equipped to adjust conventional CPM floats for the “total float paradox:” total float accumulates from schedule completion backwards; if an earlier activity consumes any of its total float, the float available for downstream related activities is correspondingly reduced.
Because GPM facilitates collaboration, it provides a renewed opportunity for communication and joint planning of a project with key subcontractors as well as the prime, a practice that over the past thirty years has taken a back seat to schedule manipulation by specialists not directly responsible for delivering the project. In contrast to past practice, GPM emphasizes experienced human judgment and collaboration in project planning instead of machine calculations. Far too often, past scheduling practice has relied on machines and software to produce CPM schedules that, although technically error-free, were not well coordinated with all stakeholders, did not correlate well with project reality and were therefore unworkable and often ignored during project execution.
© 2009 CMAA7