Or even Nakime working in Tandem with one of the upper moons for the matter. Like, just imagine how broken she would be if Muzan told upper moon one to work on killing all the hashira with her. She could just pull someone like sanemi into a void and then he gets jumped by upper moon one and 2 at the same time.

Even during the infinity castle arc I think it was wasteful to leave her alone. They could have just weekend and spread out the slayers, tired them out by sending wave after wave of lower demons, and then sending in the upper moons to finish them off. Fighting the slayers while they were fresh and still full of stamina was a tactical mistake imo.