Cash flow is the distance between the sale and the money being available. An operation can bill well and still get stuck, if traffic is paid for today and the sale's payout arrives two weeks later.
What determines that distance is the withdrawal period combined with the rolling reserve. The practical math is simple: multiply your daily revenue by the days of waiting, and that's the capital sitting idle on the platform at all times.
That's why the difference between getting paid in D+3 and in D+15 isn't a contractual detail. It's how much working capital the operation needs to run at the same volume.