The calendar is the prize, and it comes in lumps

Thirty days out, eleven days back in

Lesson 3 removed two rounds and thirty elapsed days from KA-7318. That is not the saving, because a virtual round has a calendar of its own.

Kerem needs about a day and a half to prepare and run a style. Sanna still has to look at it, and looking at it goes into her week the same way a courier bag does. Aldemere's product developers review on Tuesdays and Fridays. So the virtual sequence for KA-7318, two rounds, two reviews and the corrections in between, took eleven elapsed days.

Thirty out, eleven back in: nineteen days.

That is the honest number, and it is the one to take to a meeting. A supplier who tells you 3D saved thirty days has counted only the bag.

Nineteen days that turned into fourteen

Here is the finding of this lesson, and it is not in any brochure.

Nineteen days of development came out of KA-7318's calendar. Aldemere's autumn range review, the meeting where fabric quantities and colour splits are committed, sits in the diary every fourteen days.

A development saving becomes a real saving only where it changes a decision. The decision this one feeds is the fabric commitment, and the fabric commitment is taken at a range review. So nineteen days of saving delivered fourteen days of later commitment, and five days evaporated in the diary.

73.7% of the saving landed. The rest was real work, genuinely saved, worth nothing.

Two things follow immediately, and they change what you should be trying to do.

Shaving another two or three days off the development is worth zero. You are already sitting between meetings. Effort spent there produces a number for a report and no money.

The next increment worth having is nine more days, because that is what takes you from nineteen to twenty-eight and across a second review. That is a different project. It means attacking the review cycle itself, or a second removable round, not tuning the one you have.

What fourteen days were worth, on the style where they bit

KA-7318 was tight. The original plan had 1,900 of its 8,400 pieces going by air to make Aldemere's floor-set date, with the rest by sea. Kalthoum's freight forwarder quoted a difference of USD 1.94 a piece between the air and sea legs for this style in this season. That is a quotation to this factory for this cargo, not a rate you can carry to your own order.

The fourteen days put the whole style back on the water.

• Air freight avoided: 1,900 pieces at USD 1.94 is USD 3,686.00.
• The money saved by removing the two rounds, from lesson 3: USD 231.50.

The calendar was worth 15.9 times the money on this style. Every argument about whether a virtual sample costs a bit more or a bit less than a physical one is being held one order of magnitude below the number that matters.

And what it was worth on the rest of the range

Now the half that makes this honest.

Of Aldemere's eleven autumn styles, three were going to move part of their quantity by air. The other eight had float in their ex-factory dates: different fabrics, earlier commitments, a longer window.

• Across the three tight styles, 4,300 pieces came off the plane: USD 8,342.00.
• Across all eleven styles, the money saved by removing rounds was USD 2,546.50, before any digital cost is paid.

So the programme's calendar prize was 3.28 times its gross money saving. On the eight styles with float, the same nineteen days were worth USD 0.00.

The calendar prize is lumpy. It is enormous where a date binds and exactly nothing where it does not, and it is paid on a minority of your range. A business case that spreads an average saving across every style is describing a range nobody has.

The other thing days can buy

Days do not have to be banked. They can be spent.

Two of Aldemere's eleven styles were genuinely difficult, a bias-cut skirt and a dress with a drawn-thread panel, and both had a history of needing a round more than the calendar allowed. Kalthoum did not take the saving on those two. It spent it, running a third fit round that the old calendar could not fit.

That is the use of time nobody puts in a business case, and it may be the best one available. A style that ships with a fit nobody was quite happy with does not show up as a cost anywhere. It shows up as a return rate, in another department, next season.

Act as a merchandising manager who has to defend a saving to an owner and expects to be challenged on every line. Help me work out what the days my 3D programme saves are actually worth. My development today: [FOR EACH PHYSICAL ROUND — NAME, COST, ELAPSED DAYS FROM STARTING IT TO HAVING THE BUYER'S COMMENTS BACK]. Which rounds I propose to replace: [NAMES]. My virtual sequence: [NUMBER OF VIRTUAL ROUNDS, PREPARATION DAYS EACH, AND HOW LONG MY BUYER TAKES TO REVIEW ONE]. My buyer's decision cadence: [HOW OFTEN THE MEETING THAT COMMITS FABRIC, QUANTITY AND COLOUR ACTUALLY SITS]. My range: [NUMBER OF STYLES, AND FOR EACH — QUANTITY, EX-FACTORY DATE, WHETHER THAT DATE IS BINDING OR HAS FLOAT, AND WHETHER ANY QUANTITY IS PLANNED TO GO BY AIR]. Freight: [MY FORWARDER'S OWN AIR MINUS SEA DIFFERENCE PER PIECE FOR THIS SEASON, AND SAY IT IS A QUOTATION TO ME AND NOT A GENERAL RATE]. Do the following. First, compute gross days removed, then subtract the virtual sequence's own elapsed days, and give me the NET figure. Second, round that net figure down to whole steps of my buyer's cadence and tell me how many days evaporate in the diary and what percentage lands. Third, tell me how many further days I would need to cross the next step, so I know whether more tuning is worth anything at all. Fourth, style by style, value the realised days: where a date binds and air is planned, value the air uplift avoided; where the date has float, write zero and say so plainly. Fifth, total the calendar value and compare it against the money saved by removing the rounds, as a ratio. Sixth, name any style where I should SPEND the days on an extra fit round rather than bank them. Refuse to give me an average per style — show the lumpiness.

What to take away

1. Count the virtual rounds' own elapsed time. Thirty days removed at Kalthoum was nineteen days saved, and the difference is buyer review time that does not disappear.
2. A calendar saving is realised in whole steps of your buyer's decision cadence. Nineteen days against a fortnightly review delivered fourteen. 73.7% landed, and the rest was work well done and worth nothing.
3. That tells you what to attack next. Another two days is worth zero. Nine more days crosses the next review and is worth everything.
4. On the style where a date bound, fourteen days were worth USD 3,686.00 against USD 231.50 of round costs, or 15.9 times.
5. On eight of eleven styles the same days were worth USD 0.00, because those styles had float. The prize is real, large and lumpy, and it lands on a minority of your range.
6. Days can be spent rather than banked. An extra fit round on the two styles that needed one is a legitimate use of the saving, and it is invisible to every spreadsheet.