What a media plan is for

The instinct is to treat a plan as a forecast — a statement of what the quarter will do. Graded that way it always fails, because nobody can forecast an auction, and a document that is always wrong stops being written carefully.

A plan is for being wrong cheaply. It is the only place in advertising where a line can be halved, moved or deleted for the price of a keystroke. Every other place that argument can happen — a live campaign, a platform interface, a conversation after the money has gone — charges for it.

That reframing changes what belongs in the document. If the plan is a forecast, the interesting content is the numbers. If the plan is a cheap place to be wrong, the interesting content is the reasoning: what you decided, what you decided against, and what would change your mind. The numbers are the consequence.

Strip the formatting and a plan makes five decisions, and each of them is easier to argue about on a page than in an account.

How much, over what stretch of calendar — because a budget with no window attached is a number with no meaning; the same figure is generous over a quarter and thin over a fortnight.

In what currency, which sounds like bookkeeping and is not: one currency per plan is what makes the total at the top a real number instead of a sum of unlike things.

Across which platforms and in what split, which is the decision people spend the most time on and have the least evidence for.

In what order, and with what overlap — a real decision with real costs, and the one a table of monthly totals cannot express at all.

And against what definition of working, which belongs in a sentence before the first line exists, because a plan that does not say what counts as a result is a plan nobody can grade.

A line's budget should be the whole-flight total rather than a daily rate.

This sounds like a formatting preference and it is not. A plan is a statement about a flight — this much across March — and the total at the top of the page has to be the number you are actually spending. State the daily figure instead and the total becomes something the reader computes, which is exactly backwards for a document whose one structural job is to add up.

It also surfaces an arithmetic that is otherwise invisible. A line running twenty days out of thirty carries twenty days of money, and the daily rate implied by that is higher than the same total spread over the whole month. Shortening a flight raises the daily figure without anybody touching the budget field, and that is the sort of thing a plan should make you notice while it is still free to change.

It does not watch the accounts. The plan states what you intended; the reporting side states what happened; holding the two against each other is work somebody does on a rhythm they set.

Saying that plainly matters more than it seems, because the alternative is a planning surface that implies it is tracking drift and is not. A document that quietly stops being true is worse than one that never claimed to be watching, and the gap only reveals itself in the month it mattered.

It also does not reserve money. Two plans covering the same window will cheerfully add up to more than you have.

There is a point where a plan crosses into the accounts, and it is worth understanding rather than discovering.

Turning a plan into work validates everything before it writes anything: each line's dates against the window, each budget as a whole number of minor units, an account resolved for every line, each account's currency against the plan's, then the limits that bound a change. A failure at any step produces nothing at all, because a plan half-turned-into-work — three lines queued and a fourth refused — is the state worth refusing to produce.

What comes out is proposals rather than running campaigns, and the distinction holds all the way down. Connections read the accounts. A proposed change is a record first, carrying the value it would replace and the checks it passed, and it is cleared by you or by a rule you wrote. Then one more gate that is not ours: no platform write reaches a customer account until that platform has granted write access. Applying a cleared change is in private beta.

And then the plan freezes. Name, brief, window, currency and lines all stop being editable, because the document has become the record of what was drafted, and a record you can edit behind is not one. Re-planning the same window means a new plan, which costs five minutes and leaves both accounts of the quarter readable.

The numbers in a plan are obsolete within weeks. The brief is not.

Four sentences do most of the work: what the flight is for, who it is aimed at, what counts as working, and what you have already decided not to do. That last one earns its place more often than the first three, because it is the sentence that stops a well-meaning reallocation in week six by somebody who was not in the room.

A year later, the numbers tell you what was spent and the brief tells you why. Only one of those is reconstructible from the accounts.

A week of ad changes on the record is what happens after the plan becomes work, and How to write a media plan is the procedure.