The overnight lane is a flat forty per cent.

The overnight lane is the one genuinely boring decision in a bulk run. You give up knowing when the set comes back — within 24 hours, with no promised hour inside it — and you pay fewer credits. Most people pick it for anything that is not needed today and never look at the number again.

The number is worth one look, because the shape of it changed recently, and the old shape is the kind of thing a careful person works out once and then keeps using.

What the rule is

The lane bills sixty per cent of the standard price. A still costs ten credits on the standard lane and six overnight, and that holds at every size of set you can order:

• Three shots — 18 credits instead of 30.
• Four shots — 24 credits instead of 40.
• Six shots — 36 credits instead of 60.

Six credits a photo, three times over. The shot count changes what the set costs and never what a photo inside it costs, which is the same way the standard lane has always behaved.

Why that is worth saying out loud

Because until recently it was false. The discount is computed on one product and rounded up to a whole credit before it is multiplied across the run, and credits used to be ten times coarser than they are now — a still was one credit, not ten. Sixty per cent of four credits is two and two-fifths, which rounded to three, so a four-shot set paid a quarter off while three- and six-shot sets paid a third off.

That gap was real and it was worth a paragraph. It is now zero. Sixty per cent of forty is twenty-four exactly, and there is nothing left for the rounding to catch. The guard is still in the code for any future rate that does not divide evenly; at today's rates it never fires.

If you worked that out at the time and have been ordering three or six to dodge the rounding, stop. You are choosing a shot count on a price difference that no longer exists.

What to decide instead

Pick the shot count on what the product needs. Three is enough for a simple object photographed from obvious angles; six earns its keep on something with a detail worth its own frame — a clasp, a texture, a printed label. That was always the better question and it is now the only one, because the per-photo price is the same whichever you answer.

The one number that still moves with the shot count is the total, and it moves in a straight line: fifty products at three shots is 900 credits overnight, at six it is 1,800. Twice the photos for twice the price, with no discount for scale beyond the forty per cent the lane already gives you.

There is a second, quieter consequence of the arithmetic landing clean. A set that partly fails is refunded per photo, and six divides into 18, 24 and 36 without remainder, so the refund is exact. Under the old rates it could not always be, and a part-failed economy set left a credit of dust behind.

None of this changes what the set looks like, only what it costs and when it arrives. Deciding how many shots a product needs in the first place is the question worth your attention, and a catalogue run has its own rules about keeping fifty products looking like one shop.