A recipe that works reliably in strangers' kitchens has been through a process that has little in common with cooking something delicious once. The work is mostly about removing the author's own knowledge from the instructions.
The first draft assumes too much
A developer writing from memory records what they did, not what they knew. Pan size, heat level and visual cues sit in their head rather than on the page.
Testing exposes those gaps because a second cook, following the words exactly, will do something the author never considered doing.
Most early revisions therefore add cues rather than change quantities: what the mixture should look like, what sound the pan should make, what stage precedes the next step.
Repetition establishes what actually varies
A recipe cooked once might have succeeded because of the specific ingredients on that day, so anything that matters is run repeatedly.
Variation is introduced deliberately: different brands of a staple ingredient, a different oven, produce at a different stage of ripeness.
What survives that treatment gets written as a fixed instruction, and what does not gets rewritten as a range with a sensory test attached.
Cross-testing removes the author entirely
Serious testing sends the written recipe to cooks who have never seen the dish and have no contact with the person who wrote it.
Their failures are the useful output. A step that half of them misread is a badly written step regardless of whether it is technically accurate.
This is the stage most self-published recipes skip, and it is why they can be entirely correct and still not work for the people reading them.
Yields and timings are the least reliable numbers
Cooking times depend on pan material, oven calibration and starting temperature, none of which the writer controls, so they are written as ranges anchored to a visible sign.
Yields shift with how thickly something is rolled or how generously it is portioned, which is why a stated serving count is an estimate rather than a measurement.
Weights are the exception. A weight is the same in every kitchen, which is why tested recipes drift toward weights wherever precision matters.
What the process cannot fix
Testing cannot compensate for equipment a reader does not have, and it cannot make a technique-dependent dish work for someone attempting it for the first time.
It also cannot resolve genuine differences in taste, so decisions about seasoning levels are made and then stated rather than solved.
A well-tested recipe is best understood as one whose failures have been moved out of the writing and into the reader's kitchen, where they can at least be seen.