A slide says 98% success. The room relaxes. Somewhere a merchant just lost a Saturday because one operator, one amount, one hour, failed all morning.
Averages are a sales tool. They are a weak operating tool. They hide the bad day.
The number that looks healthy
Most of the traffic can succeed while a slice of it is unusable. A rail that works at noon and dies at payday. An amount band that always times out. A test ledger that looks fine while live money does not.
If you only watch the blend, you will keep the partner who is cheap on the slide and expensive in the till.
Slice before you pick
Ask for the same number cut four ways. By rail. By operator. By amount. By environment. If they cannot show that, they do not know their own factory.
Then ask what happens on the slice that fails. Who sees it. How fast the merchant hears. Whether the buyer gets a receipt or a shrug.
A partner who only reports the blend is asking you to underwrite their worst hour.
What we watch
We watch the slices because the merchant lives in them. One bad operator is not a rounding error if that is the method their customers actually use.
We will not sell you a blended success rate as proof that money moved. If a day was bad, say so. Then fix the slice.
A healthy average can still be one shop having a terrible day.