Teams behave differently as a deadline approaches, and the change is consistent enough to be planned for. The narrowing that makes a deadline effective is also what makes it costly.
Attention narrows to what is being counted
A deadline defines a specific deliverable, and effort concentrates on that deliverable at the expense of work not covered by it.
Documentation, tidying, maintenance and improvements to the process are the usual casualties, since none of them have a date attached.
The narrowing is genuinely productive for the named task, which is why deadlines work and also why the cost is easy to overlook.
Communication reduces exactly when it is needed most
As pressure rises, people cut the activities that feel optional, and meetings and updates are the first to go.
Coordination requirements move in the opposite direction near a deadline, since work is being integrated and dependencies are being discovered.
Teams therefore reduce information sharing at the point where the cost of a misunderstanding is highest, which is where late-stage failures usually originate.
Decisions get made by whoever is closest
Under time pressure, decisions are taken locally rather than escalated, because escalation costs time nobody has.
This produces faster movement and a set of choices made without wider context, some of which will be reversed later at greater cost.
Teams that work well under pressure usually have explicit rules about which decisions can be taken locally, agreed before the pressure arrives.
The final period sets the estimate for next time
Work completed in a compressed final push establishes what the team is seen to be capable of, and future planning is anchored to it.
The compression is treated as normal capacity rather than as a one-off, so the next schedule is built assuming it.
This is the mechanism by which occasional crunch becomes standing practice without any decision being taken to make it so.
Fixed dates and fixed scope cannot both hold
A deadline with a defined scope leaves only quality and effort as the variables that can absorb any underestimate.
Teams that hold scope fixed therefore consume the slack in hours worked, and teams that hold hours fixed consume it in what is delivered.
Planning approaches that let scope move as the date approaches exist precisely to make that trade explicit rather than leaving it to be settled quietly in the final week.