1.2Milestones & Manual vs Automatic Scheduling
The essentials in 30 seconds
- A milestone is a zero-duration task that marks a key event (approval, delivery) and appears as a diamond.
- Automatic mode makes a living schedule: Project recalculates dates from durations, links and constraints.
- Manual mode freezes values: useful for drafting, but it explains the “schedule that does not move”.
Running mini-case — Meriem milestones her approval stages
Meriem now tracks several client projects and must report on their major stages. On the extension project, she sets milestones (zero-duration tasks that appear as diamonds) at decisive moments: “Permit approval”, “Foundations handover”, “Site delivery”. One day, the client moves the date for delivering the drawings: Meriem changes the duration of an upstream task and sees the whole schedule shift by itself — except one task that stays frozen in place. Opening the Task Mode column, she sees that this task was created in manual mode during a quick draft. She switches it back to automatic and the date shifts. Meriem remembers: milestones as checkpoints, and automatic mode for a schedule that lives.
Standalone case for this section: it returns in the course, the diagram, the script and the 48h challenge of section 1.2.
1. The milestone, a checkpoint
A milestone is a zero-duration task that marks a key event: launch, phase approval, delivery, contractual deadline. It has no “work”; it serves as a marker and a checkpoint.
You create it by setting a duration of 0 (or via the Milestone button); it appears as a diamond on the Gantt chart. Meriem places them at the decisive stages of each project.
2. Auto vs manual mode
In automatic mode (recommended), Project calculates dates from durations, links and constraints — the schedule is “alive” and recalculates itself.
In manual mode, you freely fix whatever you want and Project does not recalculate: handy for drafting, dangerous if you forget to switch back to automatic. This is the great classic of the schedule that “does not move”.
3. Choosing the right mode at the right time
Manual for drafting, automatic for steering. You can set the default mode for new tasks (File > Options). Meriem checks the Task Mode column before concluding that a schedule is reliable.
A milestone remains a simple marker: it does not “consume” duration and does not weigh down the schedule. You link it to the relevant tasks so it sits at the right time.
🔎 Concrete example — 🔎 Concrete example — Manual for drafting, auto for steering
Choosing the mode according to the project stage:
Vague draft: manual mode (“about 2 weeks”).
Stabilized schedule: switch back to automatic.
→ set the default mode (File > Options) to automatic.Result: control milestones and a schedule that recalculates itself.
Reflex: check the Task Mode column before trusting the dates.
Section vocabulary
- Milestone
- Zero-duration task marking a key event (approval, delivery, deadline); appears as a diamond.
Simple example: Meriem places a “Foundations handover” milestone on the Gantt.
What it is not: a multi-day task used as a checkpoint.
Reflex: key event → milestone (duration 0).
- Automatic mode
- Scheduling where Project calculates dates from durations, links and constraints; the schedule recalculates itself.
Simple example: Meriem changes a duration and the whole schedule shifts in automatic mode.
What it is not: a frozen schedule that does not react to changes.
Reflex: steer → automatic mode.
- Manual mode
- Scheduling where the user freely sets dates/durations and Project does not recalculate automatically.
Simple example: Meriem spots a task left in manual mode in the draft.
What it is not: building the whole project in manual mode and being surprised it does not move.
Reflex: draft → manual, then switch back to auto.
- Checkpoint
- Approval stage materialized by a milestone, used to track the achievement of major stages.
Simple example: The “Permit approval” milestone serves as a contractual checkpoint.
What it is not: tracking major stages without any dated marker.
Reflex: major stage → a checkpoint.
- Living schedule
- A schedule in automatic mode that updates as soon as a duration, link or constraint changes.
Simple example: Meriem's schedule shifts when the client postpones a delivery.
What it is not: a schedule copied by hand into a spreadsheet, never up to date.
Reflex: living schedule = automatic.
In practice — In practice — Creating milestones and managing the mode
- Create a milestone by entering a task with duration 0 (e.g. “Specification approval”): it appears as a diamond.
- Place milestones at key project stages (end of phase, delivery) as checkpoints.
- Check each task's mode (Task Mode column): favor automatic mode for a living schedule.
- Test the difference: in manual mode, change a predecessor and see that the date does not move; switch back to automatic.
Step-by-step script — milestone and set the mode like Meriem (4 min)
1) Create a milestone: new line with duration 0 (or Milestone button), it appears as a diamond. 2) Name it after the event (“Permit approval”, “Delivery”) and link it to the relevant tasks. 3) Open the Task Mode column and check that tasks are in Auto Scheduled. 4) Set the default mode (File > Options) to automatic for new tasks. 5) Change an upstream duration and check that the whole schedule shifts.
A zero-duration milestone does not weigh down the schedule: it is a marker, not a work task.
Copy-paste template — my milestones & modes
Milestone: [ ] Permit approval [ ] Foundations handover [ ] Delivery
Milestone duration: 0 (diamond)
Task Mode column checked: yes / no
Tasks switched back to automatic: ___
Default mode for new tasks: automaticApproval milestone
Meriem creates a “Permit approval” milestone as the project's contractual checkpoint.
Draft in manual mode
Meriem quickly enters a project in manual mode, then switches it back to automatic as soon as it stabilizes.
Frozen schedule
Meriem diagnoses a “schedule that does not move”: a task has remained in manual mode.
Default mode
Meriem sets the new-task mode to automatic to avoid the trap at every creation.
✓ Best practices
- Set milestones (duration 0) at key stages.
- Work in automatic mode for a living schedule.
- Set the default mode for new tasks to automatic.
✗ Common pitfalls
- Building the whole project in manual mode.
- Forgetting to switch back to automatic after drafting.
- Being surprised that the schedule “does not move” (tasks in manual mode).
Key takeaways
- A milestone is a zero-duration task (diamond) marking a key event.
- Automatic mode = Project calculates the dates (living schedule): recommended.
- Manual mode = you fix everything, Project does not recalculate: useful for drafting, risky if forgotten.
- Most “the schedule does not move” cases come from tasks left in manual mode.
48h challenge — apply it tomorrow
On a current project, set at least three milestones (duration 0) at key stages and check the Task Mode column: switch any task left in manual mode back to automatic. Write in one sentence what happens when you forget manual mode.
- I can create milestones (zero-duration tasks) and place them at key stages.
- I can distinguish automatic and manual scheduling.
- I can diagnose a schedule that “does not move”.
Frequently asked questions
Why doesn't my schedule update when I change a duration?
In the vast majority of cases, the task is in manual mode: Project then respects what you entered and does not recalculate. Check the Task Mode column, select the relevant tasks and switch them to Auto Scheduled. Tip: also set the default mode for new tasks (File > Options) to automatic.
When should I use manual mode rather than automatic?
Manual mode is useful in the drafting phase, when information is unclear: noting an approximate duration, an uncertain target date or setting tasks without a known sequence. As soon as the schedule stabilizes, switch back to automatic to benefit from recalculation and, later, from the critical path. Manual for drafting, automatic for steering.
What is a milestone in a schedule?