I'm not very good with judging grind sizes, so one method I read about was, instead of focusing so much on grind size pay attention to the brew time. If the brew takes too long, the coffee grounds are too fine, but if the brew time is too short then the coffee is too coarse.
I really like this method, and the estimated ranges I've come across for pour over is 2:30 mins to 4 mins (i.e., it should be no faster than 2:30min, but take no longer than 4 mins)
So far, I feel like around 3 mins is the sweet spot for my usual choice of coffee and a 3-cup Chemex.
Is there just one ideal brewing time (or time window) or does that differ depending on the roast or other factors? How would I recognize a too long or too short brewing time in the finished product?