1. Different coffee beans will extract differently
2. Using more water will result in weaker coffee but higher extraction. Using less water will result in stronger coffee but less extraction.
3. The grind setting needs to scale with the amount of coffee you make. For example, brewing 30g of coffee requires a coarser grind as compared to 12g.
4. The temperature of the water will affect your extractions. Cooler water will extract slower and hotter water will extract faster.