Why You Need To Stop Breaking The Laws Of Physics In Your Project Schedules

In Project Management, a project schedule is a comprehensive timeline of tasks, milestones, deliverables, and required resources for completing a project. In reality, a schedule, such as a Gantt Chart, is meant to keep you on track for your project; however, project managers often fail to link schedule elements to the dependency hierarchy model.  

We look at a project schedule and see a collection of bars on a screen. We forget that those bars represent physical reality. If you treat every link between tasks as a flexible suggestion, your project will collapse long before the delivery date.

This begs a critical question. When the pressure hits, which rules can you actually afford to break?

The Dependency Hierarchy

You cannot blindly fast-track your project. You must understand the hierarchy of dependencies.

• What is practised: Every task link is an absolute constraint that must be respected equally.

• What is missing: The intelligence to distinguish between dependencies that cannot be moved and those that are preferential in nature.

• What exists: Schedules that treat an administrative delay with the same consideration and gravity regardless of the types of dependencies.

• What is needed: A brutal assessment of the five dependency types to find your hidden float.

  
  

Logical Dependencies

These are the hard, non-negotiable laws of nature. You cannot make an omelette without breaking the eggs. You cannot put a roof on a house before you build the walls. These links between the tasks are non-negotiable. If you try to fast-track a logical dependency, you are not managing a project; you are finding ineffective shortcuts.

Mandatory Dependencies

These types of dependencies are your legal, contractual, and business processes requirements. Your company policy might dictate a formal tender process before hiring a contractor. You can technically side-step these rules to save time. But doing so destroys the quality of your output and invites a catastrophic audit.

External Dependencies

These are the elements entirely out of your control. Often stemming from external stakeholders, it could include waiting for hardware delivery from a third-party vendor, waiting for an approval from a client partner or needing government environmental hearings to conclude. You cannot overlap these. You can only build proactive risk management into your timeline to absorb the inevitable delays.

Internal Dependencies

These are your resource constraints. It is logically possible to run a critical workshop on Monday, but your expert facilitator is only available on Wednesday. Internal dependencies have flexibility. You can solve them, but it usually requires spending more money to acquire more resources.

Discretionary Dependencies

These are simply your team's preferences. You might schedule exterior painting before interior work, so your team can move inside if it rains. It is a good habit, but it is not a law.

When you need to compress a schedule, discretionary dependencies are your goldmine. You start here and work your way up.

The Trap of the Central Planner

But how do you actually know which dependencies are merely discretionary?

Most project managers sit in a quiet office, stare at a dashboard, and make decisions based on their experience and prioritisation needs. They decree that testing will start concurrently with development. This centralised guesswork harms team productivity. A central planner cannot see the ground-level reality. They cannot see that what appears to be a preference on a spreadsheet is actually a rigid technical constraint in the real world.

To survive a compressed schedule, you need to have an inclusive decision-making process.

You must decentralise the choice. Bring the engineers, the builders, and the task owners into a room. Show them the schedule constraints. Let the people doing the actual work identify the discretionary links. They know exactly which processes can be safely overlapped and which ones will trigger a disaster. When you rely on team input, you stop dictating fiction and start managing reality.

Look at the overlapping tasks on your screen right now. Are you breaking the laws of physics, or just a bad habit?

Stop guessing your schedule constraints.

Join our live webinar on Decentralised Decision-Making this June 13th.