Managed by dates
- One date per task, a hidden margin buried in each one.
- Margins burn down without warning, task after task.
- The delay only shows up at the end, too late to act.
Flow · Theory of constraints
Manage by work-in-progress, not by dates.
Dozens of projects running in parallel, tasks scattered across dozens of people, deadlines slipping, and management with no visibility: that's daily life in an analytical development lab. Managing by dates collapses here. There's another way, inspired by Goldratt's critical chain: manage by work-in-progress (WIP) and its age.
80 · 50 · ∞
≈ 80 projects in parallel, ~50 people involved, dozens of deliverables per project: a combinatorial load that no individual date can hold.
When every task carries its own due date, you think you're in control — but all you're doing is stacking up promises. No one knows which task to work on first, each project's margin burns down silently, and delays only become visible once they've already been consumed. The theory of constraints proposes the opposite: stop managing dates, and manage flow.
The real problem
Everyone has a date. No one has a priority.
At the scale of dozens of simultaneous projects, task dates become noise: they contradict each other, go stale, and never tell you where to put the effort right now. The result: everyone optimizes their own task, no one optimizes the flow, and projects drag on without anyone knowing which ones are truly at risk. Management runs schedules, not reality.
The turnaround
From dates to aging work-in-progress.
We drop task dates and manage the color of the WIP item — which depends on its age since its first step.
Managed by work-in-progress
- No task date: you track the age of each WIP item.
- A color flags the overall margin consumed, in real time.
- Simple rule: "first overdue, first out."
The principles
Four ideas, borrowed from flow.
The plumber's metaphor: pipes, flow rates, water slides.
Know your work-in-progress
You can only control a flow if you can see what's in it: every deliverable in progress, and for how long.
First overdue, first out
You push the oldest, most disrupted WIP items first, to bring the flow back to normal.
The sub-process is a water slide
"No stopping, no overtaking": once launched, a deliverable goes all the way through, with no internal queue.
Variable capacity
You allocate capacity, as a team, to the most overdue tasks — rather than rigidly dedicating resources.
The legacy
The critical chain, in practice.
A concrete application of Eliyahu Goldratt's theory of constraints.
The critical chain teaches you to pool the margins instead of hiding them in each task, and to protect the flow with a shared buffer rather than individual dates. Managing by aging work-in-progress is its operational translation: you no longer manage deadlines, you manage the consumption of an overall margin, visible at a glance through color. Management finally regains real visibility, and delivery becomes reliable.
How we roll it out
Managing delays, as a team.
Map the flows
Identify the sub-processes (the "water slides") and the deliverables that run through them, at the portfolio level.
Visualize WIP age
A management tool colors each WIP item by margin consumed: green, orange, red.
Decide in a team ritual
A regular check-in steers available capacity toward the most overdue WIP items. The team runs the flow together.
Go further
Flow, everywhere things drag.
Flow
Reduce batch release time
The same flow principle applied to the batch record: from 60 days to a few hours.
Read the article → Quality controlWorkload & capacity in the QC lab
Manage workload and capacity against growth, without overloading the teams.
Read the article → ConsultingOperational performance
Make the delivery of your projects and flows reliable, end to end.
See the approach →Frequently asked questions
Managing by work-in-progress & the theory of constraints.
Developed by Eliyahu Goldratt, the theory of constraints (TOC) holds that a system's performance is dictated by its bottleneck: that's what you need to identify, protect and exploit. Applied to project management, it gives the "critical chain": you protect the overall flow with a shared buffer rather than protecting each task with its own margin.
Because at scale, task dates contradict each other and mask the real urgency. By replacing them with tracking of WIP age and an overall margin, you make the priority obvious: you handle whatever is most overdue first, instead of chasing deadlines that are already stale.
It means running a project portfolio by tracking, for each deliverable in progress, its age since its first step and the margin consumed — shown as a color. The team then steers available capacity toward the most overdue WIP items, following the rule "first overdue, first out."
Especially so: analytical development combines many simultaneous projects, varied deliverables (methods, specifications, stability studies, monographs) and resources shared across dozens of people. It's an ideal setting for managing by work-in-progress, which gives management back its visibility and makes delivery reliable.
Stop chasing dates. Manage the flow.
Let's look at how managing by work-in-progress can make your analytical projects' delivery reliable.