Back then, many boards used to be routed with vertical traces on one layer and horizontal traces on another, "Manhattan routing". Somehow, the circuits worked. Nowadays you can't be so "careless" to hit EMI targets or even to get a working board. Switching PSUs, data buses, clock signals, all those have spacing, impedance control, ground coupling and other requirements.

Maybe you could encode all of them in the schematic and then let a modern algorithm suggest a board layout, but in practice nobody seems to do it that way (note that I am just a hobbyist with limited experience).