Common Primavera P6 Scheduling Mistakes

Constraints used to force dates

The single most common mistake: applying hard constraints to make activities land on desired dates, overriding the logic. It produces a schedule that looks on-target and tells you nothing when things change. Most constraints should not be there.

Open ends and dangling logic

Activities missing a predecessor or successor break the network so delay no longer flows through it. A programme full of open ends has a critical path that cannot be believed.

Negative lags to fake overlap

Using negative lag to force activities to overlap distorts the network and flatters the finish. Model the real overlap with proper relationships instead.

Durations with no basis

Durations estimated by feel — every activity a round 10 or 20 days — signal a programme built to look complete rather than to be built. Durations should trace to a quantity and a resourcing basis.

Progress that doesn’t reconcile

Updating percent-complete without honest actual dates, or leaving actuals in the future and forecasts in the past, means nothing calculated from the schedule can be trusted. Discipline in the update is as important as discipline in the build.

The fix is a standard

None of these needs genius to catch — they need a consistent quality standard applied every cycle, ideally automated. Run a programme against the schedule health checklist and these mistakes surface before they cost anything.