Why do nuts generally have to be hexagonal?

Threaded fasteners generally act as a fastening for the machine. The position and size of the assembly is often limited by space, which means that the assembly space is small. In the case of insufficient space, use a wrench to tighten the nut, the angle of a single rotation is obviously as small as possible. Assuming that the nut has n sides, the angle at which each wrench rotates is the degree, so the number of sides increases and the angle of rotation decreases, which is advantageous for operation. However, in practice, simply increasing the number of sides will reduce the contact area between the wrench and the nut, making it easier to slip. After the experience of the predecessors, the hex nuts that are easy to operate (single turn 60 degrees, 90 degrees compared to the four corners) and not easy to slip are selected.