So, we use our ideal settings for dose, time, and temp as rather fixed and then tune the grind to adjust volume as needed.
The same approach is taken with Syphon as it is with all hand pour methods we work with. Find an ideal set of parameters and work backwards. Determine an ideal temperature relative to dose, timing, and volume.
For our Syphon methods, grind is easy to adjust. Once you choose a dose, temp, and brew volume relative to a specific time. In this instance, we choose the draw down time as the coffee comes from the top to the bottom globe. We treat it as a fixed value which for our method, relative to our specific dose and time, which is 30 seconds. Change the brew time or dose significantly and this value of 30 seconds becomes a bit arbitrary, needing a recalibration.
For v60 and other free pour methods like the Cloth Flannel Woodneck, grind is not alone in affecting the brew volume. The pour rate has a large effect.
For beginners to v60, we recommend using a scale underneath to measure pour rates. Rather than using it for resulting brew volumes, we use it as a measure to know for certain we have (for example) poured 6 ounces in the first minute. Knowing the rate of pour is a good way to pin that down as a variable and then adjust the grind.
In the same way as we do the Syphon, we choose the last 30 seconds for draw down in the one cup method as a point for grind calibration. If we stop pouring at 30 seconds and the last drips flow through before the time is up, the grind is too coarse. If there is substantial water left, the grind is too fine.
This is, of course, subjective to dose and whether the pour itself created an even dispersion of grinds in the filter bed.
The summary being, we attempt to hold all variables firm to the only one that is most effective in compensating for environmental variables, the grind. The grind has an effect on flow and resulting brew volume so the key is constantly adjusting the brew volume back towards ideal throughout the day with a fixed dose, time, and temp.