Not an AE, but from my understanding of orbital mechanics, I think we usually use a LEO orbit to insert payloads into higher orbits or onto escape trajectories.

Not an AE, but from my understanding of orbital mechanics, I think we usually use a LEO orbit to insert payloads into higher orbits or onto escape trajectories. Even Starship, which could be considered a next gen orbital vehicle, relies on LEO for reloading fuel before leaving Earth.