Это, оказывается, иллюстрация к недоступности третьего класса точности для домашних условий (It's tough to line up the drill with the via holes for the through-hole components. Being slightly off can pull-up or drill-out a lot of the copper pad. This reduces the contact the solder and through-hole wire can make with the circuit. With this in mind, extend the diameter of via pads for hand drilling).