The Profit First method recommends using percentages to manage cash flow even if a business's income is inconsistent because it allows business owners to establish a consistent system of allocating funds, regardless of the amount of money that is coming in.

When you use percentages to manage your cash flow, you are essentially setting aside a certain percentage of your income for specific purposes, such as profit, taxes, and reserves, before you pay your bills.

This helps ensure that you are consistently paying yourself first and setting aside funds for important business expenses, even if your income varies from month to month.

For example, if you allocate a certain percentage of your income for profit and another percentage for taxes, even if your income varies you will always have funds set aside to cover those expenses. This system of allocating funds by percentage ensures that your business will maintain a consistent flow of cash, even if the amounts of cash coming in vary.

It's important to note that, when using percentages, it's suggested to adjust them based on the actual needs of your business, as certain percentages might not be suitable for every situation. Additionally, monitoring your cash flow regularly, and making adjustments as necessary, can help ensure that your business is always in a strong financial position, regardless of how much money is coming in.