The concept

The withdrawal period is the time between a sale's approval and the moment the corresponding amount becomes available for the seller to withdraw. This period is commonly expressed as D+n, where D is the day of the sale and n is the number of calendar days until release, such as D+3 or D+15.

Longer withdrawal periods dam up working capital: the sale's money has already happened, but it can't be reinvested in ads or operations until it's released, which directly affects the cash flow of anyone selling every day.

How it shows up in practice

You make a sale to an international customer today. The transaction is approved and the money is technically yours. But the payment platform announces that the withdrawal period is D+n, meaning you can only withdraw to your bank account some days later. If you sell regularly, you end up having part of your revenue held up on the platform, capital you could be using to pay for ads, pay affiliates, or pay suppliers.

Ultimately, the business that can spend the most to acquire a customer wins.

Dan Kennedy Source: quoted by Russell Brunson in DotCom Secrets.

The shorter the withdrawal period, the faster you have cash flow freedom. Platforms with shorter periods let you move money faster. If you have a large operation with continuous withdrawals, the difference in periods is the difference between running smoothly and being stuck with capital held up.