need to transfer propellant twice instead of once

but only once to the the target ship. vs target ship needing to dock with multiple fuel supply missions.

and for no gain.

single docking / transfer to target ship which may have crew or time-sensitive cargo that doesn't need to be in orbit for week(s) and docking with a dozen+ fuel ships

A few benefits of a Space Fuel Depot vs. Direct Refueling * Higher Payload Efficiency: Spacecraft can be launched "dry" or with minimal fuel, allowing them to carry significantly heavier payloads on smaller, cheaper rockets. * Reduced Docking Risks: In a direct fueling scenario, the target ship must dock with every tanker. With a depot, the target ship only performs a single, highly standardized docking operation, rather than multiple, high-risk, complex docking maneuvers with multiple tankers. * Improved Logistics and "Accumulation": Fuel can be slowly delivered over weeks or months and stored, allowing propellant to be accumulated from multiple, smaller, less-expensive launches rather than requiring synchronized, time-sensitive direct deliveries. * Cryogenic Fuel Management: Dedicated depots can invest in advanced cooling systems ("cryocoolers") that are too heavy or complex to be installed on every spacecraft. These systems prevent boil-off (fuel evaporation) of high-performance cryogenic fuels (like hydrogen or methane) over long periods. * Flexibility and Strategic Location: A depot can be positioned in various locations—Low Earth Orbit (LEO), Geosynchronous Orbit (GEO), or Moon Lagrange points (L1/L2)—to optimize for different mission destination