Every individual setup works differently in terms of finding an optimal extraction efficiency. I use 21g laser cut baskets, dosing between 20g and 25g - depending upon the coffee, the bean age and style of coffee I want at that moment (I dose differently for espresso compared to ristretto), from a large commercial conical grinder and extracted on a rotary pump driven espresso machine. The dynamics of what works for me in adjusting my shot may not help or even be valid for a different type of machine such as a lever, different basket sizes, flow rates, brew temperature and quality of the grind (defined as those who may run an empty bean hopper and weight their shot dose beforehand, allowing for low or almost zero downward pressure being applied to the beans on the burrs during the grinding stage). The bean is very hard and it's a medium roast to preserve fruit characteristics. Typically (but not true in all cases) when you down-dose a hard bean and the ratios are not right, you increase the risk, extent and impact of channeling. The key is inspecting pucks and combining with the cup taste - that is the only way to learn and adjust techniques that can lead to improvements on your own kit. Personally, I don't run empty hoppers as the majority of grinders with their horizontal orbits do not work effectively - empty hoppers are intended for a different style of grinder. For me, dose weighing is only performed randomly by measuring the zero tare of a portafilter before locking in for a shot. My adjustments are made based on eyesight (the pour), resultant color and taste.
