Recipes specify quantities precisely and heat imprecisely. That asymmetry is deliberate, and understanding it changes how the instructions should be read.
Hob output is not standardised
Burners differ substantially in power between gas, electric and induction, and between models within each type.
A setting described as medium delivers different amounts of energy on different hobs, and the same dial position produces different results with different pan sizes.
A recipe writer therefore has no reliable way to specify heat as a setting, since the instruction would be wrong for most readers who followed it.
Pan and quantity change the effective heat
The same burner under a thin pan and a heavy one produces different surface temperatures, and the difference is large enough to change the outcome.
Quantity matters equally, since a pan crowded with cold food loses heat faster than the burner can replace, while a nearly empty one runs hot.
These interactions mean the useful variable is the temperature at the food, which no dial reports directly.
Good recipes describe behaviour instead
Precise instructions in this area are sensory: the onions should sizzle steadily rather than spit, the liquid should show occasional bubbles rather than a rolling boil.
Those descriptions transfer between kitchens because they describe the food's state rather than the equipment's setting.
A cook who adjusts the dial to produce the described behaviour has calibrated their own hob, which is what the instruction was asking for.
Oven temperatures are stated but still approximate
Ovens are specified in degrees because they hold a set point, though most domestic ovens run some way from the number on the dial.
They also cycle around that point rather than holding it steadily, and they heat unevenly depending on where the element and fan sit.
Which is why oven recipes give both a temperature and a visual cue, and why the cue should win where the two disagree.
Reading for state rather than for time
Times in recipes are estimates derived from one kitchen, and treating them as instructions produces the familiar problem of food that is not ready when the recipe says it should be.
Reading the stated time as a prompt to start checking, rather than as a moment to stop cooking, resolves most of that mismatch.
Recipes that give only times and no descriptions of state are harder to follow accurately, whatever else they get right.