How aggressively do you want to keep aligning with your Asset Allocations? As part of the rebalancing function of the Sheet, this will tell the Sheet how aggressively you want to rebalance and assign future income.
For example if you are deficient in ETFs by 10% according to your allocations, set to light the Sheet may only recommend 30% of your next paycheck contributed towards ETFs. If set to aggressive, the Sheet may recommend up to 100% of your next pay check.