That's not a scale indicator. Chequed neatlines are best thought of as an extension of the graticule, the grid showing latitude and longitude, or some other coordinate system like UTM.

Drawing one correctly depends on the extent and projection of your map the same way that the graticule does. Drawing one wrong can say things about your map you may not want to say, and may even contradict other parts of the map.

The one in your example appears to be modelled on a modern road map street locator and suggests it's part of a larger road atlas because it isn't aligned to the map. This contradicts the style of the map though. There's also no graticule which is really odd for a map with a chequed neatline. There are sometimes situations that might justify it but it's very unusual.

Not all of the things you see on maps belong on all maps.