Episode 4: The Lag That Laid a Trap

“How a careless lag caused a six-week delay.”

🏗️ Scene: A Question with No Answer

“Why is the main façade still not started?”

That was the question from the construction manager. And I didn’t have an answer. The last update said all preparatory works were done. The subcontractor was ready. Yet the schedule showed a six-week gap before their start.

I pulled up the file. Searched for the façade task. And there it was:

“Start Façade Works” – FS + 45d lag.

Someone had inserted a fixed lag. No comments. No justification. Just a 45-day delay buried in logic.

🧠 The Root Cause

This wasn’t new to me. In Confession of a Project Scheduler, I warned about this:

“Lags are lazy logic. If you can’t explain it, you shouldn’t enter it.”

This 45-day lag had no basis in site conditions, procurement, or approvals. It was a leftover from a temporary workaround. The scheduler had tried to “space out” activities to match expected site tempo—and forgot to clean it up.

That forgotten lag triggered a chain of delays.

🔥 The Fallout

• Façade contractor demobilised due to unclear timeline.
• Site team faced rework as scaffolding was removed prematurely.
• Delay claims surfaced, blaming poor planning.
• Scheduler credibility took a hit.
• All because of one silent, unjustified lag.

📌 The Lesson

• Every lag is a loaded gun.
• If you use one, make sure you know exactly what it’s aiming at.

✅ Pro Tips for Schedulers:

• Replace lag with explicit tasks: If there’s a reason for delay, show it as an activity.
• Document every lag: Who requested it? Why? How long?
• Audit your logic paths: Use filters to find long lags and review them regularly.
• Use buffers wisely: Never confuse float with fixed lag. Build resilience with transparency.
• Flag suspect logic in review meetings: Don’t let hidden lags escape discussion.

🕵️ Quote Board

“Lags are like landmines. Invisible until they explode.” — The Scheduler”

“A six-week delay isn’t always from site—it could be hiding in your logic.” — Planning Auditor”

📚 Coming Up Next:

Episode 5: The Task That Wouldn’t End“
Why ‘95% complete’ stayed on screen for three months.”