Good point. If the bunch is a good size I divide in half, then break in half and put into the blender. That's bout 2 good handfuls. I weight about 123 lbs, but don't know if weight is an issue in the amount needed. Others use more or less; very subjective. I mentioned an earthclinic GD sufferer was going on a 6 year initial breakout (longer than most have the primary breakout) and he was using 6 bunches a day and it was working for him. First time in 6 years he was getting relief. Very inspiring to read the earthclinic site on Grover's. Try the 2 handfuls a day, if it doesn't help after a few weeks increase it.
I know which stores have the freshest and biggest bunches and the best value, often only stopping in their for the cilantro. I learned it is best to stock up before New Years or Cinco de Mayo as the shelves run dry. I also learned from others to freeze individual servings so if I find giant bunches that look super fresh I buy extra instead and this comes in handy. Stems work great, I trim just a minimum off the end tips and toss before storing in about 1/4 inch of water or less in mason jar covered in a loose plastic bag with slits cut for circulation in the refrigerator.