A vertically alternating sequence of continuous insulating layers and continuous sacrificial material layers is formed over a substrate, and is patterned to form stepped surfaces. Memory stack structures are formed in a memory array region of the alternating stack. Support pillar structures are formed through the vertically alternating sequence within a staircase region. The support pillar structures are formed at lattice sites of a hexagonal lattice structure that includes unoccupied lattice sites. Portions of the continuous sacrificial material layers are replaced with electrically conductive layers. Contact via structures are formed on a respective one of the electrically conductive layers at the unoccupied lattice sites. Geometrical centers of the support pillar structures are arranged at vertices of a polygon having more than four vertices having a respective contact via structure located at a geometric center of the polygon in a plan view.