You've got a great designer on your team. Their work is awesome, highly detailed and always right on target. They love to test optimizations to their initial work. You wish you had two more designers just like her.
Well since hiring is hard and cloning is even more difficult, i've got a slightly different approach: ask her to provide less fidelity in her designs. To do less testing and optimization. To think about each project for shorter periods of time.
What? An affront to the art of creation!
Not really, rather just banking on intuition of smart people. I rather have the partial intuitive attention of a superstar to bang out some highlevel wireframes than the fully detailed mocks of a lesser talent. And if i've found a superstar, i want their productivity to be high - so guide them to focus on the details only in the most important cases, and turbocharge their output by timelimiting other exercises. You don't want engineers backed up waiting for designs, and some hastily constructed thoughts from a great designer will be remarkably better than what most people can produce, even if given all the time in the world.
I find this approach also works with product managers - a quick direction spec and prioritization from someone who knows their stuff will always beat a more detailed PRD from a more average talent.
So if you ever look longingly at someone on your team and wish you had another person just like them, think about how to increase their output by getting them to do less, not more.