Your Assumptions Will Sink the Project: A Checklist for This Week
Most projects do not fail on the work that was planned. They fail on the things everyone assumed and nobody wrote down: that the vendor would deliver on the date verbally promised, that the key approver would still be in their role, that the team could keep working the way it did before. Assumptions are not optional — you cannot plan without them. But an unexamined assumption is just a risk wearing a disguise, and right now, with supply still shaky and teams spread across kitchens and offices, the disguises are working overtime.
The good news is that managing assumptions is a habit, not a heroic effort. Here is a checklist you can run this week, on a project you already have open.
Surface them
Write down what has to be true. Take your current plan and list every condition it depends on: deliveries, approvals, availability of people, stable requirements, third-party performance. If a statement in your plan would collapse should one fact change, that fact is an assumption.
Name the owner of each one. An assumption with no owner is nobody's problem until it explodes. Beside each one, put the name of the person closest to the truth — the one who would notice first if it stopped being true.
Mark how confident you actually are. Rate each assumption high, medium, or low confidence, honestly. The low-confidence ones that also carry big consequences are where your attention belongs.
Test and track them
Validate the cheap ones now. Some assumptions can be turned into facts with a phone call or an email this afternoon. Is the part actually in stock? Is the approver actually back from leave? Do that first; it is the highest-return hour you'll spend.
Convert the rest into risks. Any assumption you cannot validate cheaply belongs on the risk register, with a trigger ('if confirmation hasn't arrived by the 5th') and a response ('switch to the backup supplier'). That is how an assumption stops being a silent liability.
Set a review date, not a hope. Assumptions decay. Conditions true at kickoff quietly stop being true. Put a recurring line in your status review: 'which of our assumptions changed this week?' and actually answer it.
A practical tip on phrasing: write assumptions as testable statements, not vague comfort. 'Supplier will deliver castings by November 12' can be checked. 'Supply chain should be fine' cannot, and that vagueness is exactly where projects hide their biggest exposures.
Why this pays off
When an assumption fails on a project that never named it, the team scrambles, blame circulates, and the schedule absorbs the hit. When an assumption fails on a project that listed it, owned it, and watched it, the trigger fires, the planned response kicks in, and the disruption becomes a managed event rather than a crisis. Same bad news; very different day.
Keep the assumptions log short and visible — a buried list nobody opens does nothing.
Re-run this checklist at every major phase boundary; new phases bring new assumptions.
Treat a validated assumption as a fact and remove it, so the live list stays meaningful.
You will not eliminate uncertainty — no one can. But you can stop being surprised by the parts of it you already suspected. An hour with this checklist this week is cheaper than a recovery plan next month.
When the assumptions stack up faster than your team can track them, XNM's program & project delivery advisory can help you build the discipline that keeps surprises from becoming setbacks.