The unit fractional marketing sells is time. Nobody asks what it's accountable to.

Every fractional pitch eventually gets to the same number. Two days a month. Four days a month. A day a week. The arrangement is always described in time.

Compare that to a full-time hire and the maths gets loud fast. A £120,000 salary, once you add employer national insurance and pension, runs closer to £140,000. Add recruitment, benefits, the months it takes to onboard someone senior, and a fractional day rate looks like the obvious saving.

It probably is a saving, on the number being compared. But look at what's actually being sold on either side of that comparison. Days. A fraction of a working week against a full one. Neither number says what's owed in return.

The arrangement isn't the question

Permanent, part-time, interim, it makes no real difference to the result. What decides the result is the number the work starts from. A full-time hire who opens with pipeline and revenue targets produces the same outcome as a fractional CMO who opens with the same brief, just at a different day rate.

The arrangement is a distraction from a simpler question. Whoever's doing the work, accountable to what?

What "days bought" leaves out

I've never seen a fractional pitch that says "we're accountable to moving your CLV:CAC from 1.8:1 to 2.6:1 inside two quarters." I've seen plenty that say "two days a month, strategic input, senior expertise." All true. None of it a commitment to a result.

That's not quite fair to the pitches, though. Most do propose a measure they'll be held to. Leads generated. Pipeline influenced. A share of revenue. The job spec for a full-time hire reads the same way: demand generation, revenue contribution, growth. Someone is trying to attach an outcome to the days.

The trouble is which outcome. Revenue is a line on the P&L, and in most businesses it's already owned by the commercial leader closing the deals. Marketing reaching for a share of it, however the attribution model is built, is marketing trying to prove a hand in a number somebody else is already accountable for. That's not a measurement problem. It's an ownership problem, and no framework fixes it, because two functions can't own the same line.

The reason every pitch and every job spec ends up in that language, demand, leads, revenue contribution, isn't that nobody's tried to attach marketing to a number. It's that revenue and pipeline are the only numbers finance already recognises. Nobody has ever handed marketing a number of its own that finance would accept in the same way.

Time bought and time delivered is the easiest contract in the world to fulfil. It's also the easiest one to fulfil without changing anything that matters.

That's not a criticism specific to fractional work. A full-time marketing hire, permanent, on a salary, with a title and a seat at the leadership table, faces exactly the same gap. The employment structure changes who invoices whom. It doesn't touch what either of them is actually being asked to move.

How the pitch actually reads

Look closely at a typical fractional proposal and it isn't short of outputs. Leads generated. Pipeline influenced. Revenue contribution. Growth, dressed up in whichever word survives that quarter's argument. Every proposal has a number attached, it just happens to be the same number every time, and it's the one already spoken for.

Full-time job specs read the same way. Seniority, scope, reporting line, salary band, and then the same three or four output words: demand, pipeline, revenue. A CMO hired against that brief can spend two years in the role and leave with the business no clearer on whether the acquisition engine got healthier or worse while they were there, because the number they were measured against was never theirs to own in the first place.

Why the days-bought model survives anyway

It survives because time is easy to sell and easy to buy. A day rate is comparable across providers, quotable in a single sentence, and doesn't require either side to agree on what success looks like before the engagement starts. A capital outcome is none of those things, at least not without doing the harder work first.

It also survives because most businesses buying marketing leadership, fractional or otherwise, have never been shown a number that would let them ask for anything more specific than time and seniority. You can only negotiate the terms you know exist.

What changes if you ask a different question

Before agreeing to buy time, ask what the fully loaded cost of winning a customer is against what that customer is worth. That's the CLV:CAC ratio, and it's the one number that tells you whether the acquisition engine is creating value or quietly destroying it.

Once you have it, the days-bought question answers itself. A ratio below 1:1 needs urgent, focused work, whatever the arrangement. A ratio above 3:1 might not need a fractional leader at all, just discipline in what's already working. Neither of those is a question of days per month. Both are questions the ratio answers and the day rate never could.

None of this requires abandoning the fractional model, or the full-time one. It requires putting the ratio in front of the arrangement, rather than the other way round, so whoever ends up doing the work knows from day one what they're actually being asked to move.

The arrangement was never the thing to negotiate. The number was. Fix that first, and whether the person doing the work is full-time, part-time or in the room for a single quarter stops being the interesting question.