One recipe, learned properly
Why we ship a single V60 recipe with every lot instead of a chart of variables.
The recipe is 15 g of coffee, 250 g of water at 94 °C, ground medium-fine, finishing the drawdown at 2:45. Rinse the filter and warm the brewer. Bloom with 45 g for 40 seconds. Pour to 150 g, then to 250 g once the bed settles.
That is the whole thing, and it is deliberately one recipe rather than several. Brewing variables interact. If you change dose, grind and temperature at the same time and the cup improves, you have learned nothing about which change did it.
So keep the recipe fixed and read the cup. If it tastes thin, sour or salty, the water left too early: grind finer, or pour a little slower. If it tastes harsh, dry or hollow, it stayed too long: grind coarser, or stop earlier.
One adjustment at a time, then brew it again. The same coffee, the same recipe, twice a day for a week will teach you more than twenty recipes tried once each.
When the next lot arrives the numbers may change, because a different variety and a different process want a different extraction. We will print the recipe we settled on with it.