This is a very important point. A lot of people think that you need a fine grind for brewing in a cup, but that's not true. You need a coarse grind, why? Because the contact time with water is very long, and that's where the coffee continues to brew. If we have a fine grind in the cup your coffee will over-extract, meaning the coffee will give up too many substances that will bring bitterness to your drink and it won't be balanced.