For those who don't know, there are special checkering files made to do the task.
There is the simple single blade V file and then, there are spaced files. Rather than having just one V shaped cutting file, they have two V's, spaced to give the distance between the grooves that the user wants the checkering to end up at.
There is also a file with one smooth V without teeth and one V with teeth. This file is used to follow a previously cut V and form a new V at the correct distance.
Great care must be given when using any of these files to checker a stock. Even with the spaced V' type file, if the V that is following a previously cut groove jumps out of it's groove, the second V file will cut a new, incorrect groove. Care also has to be given to follow the curvature of the stock, keeping the cutting edges square with the wood at the point where the file is cutting.
The most difficult part of checkering is forming the grooves where the checkering ends. While the last long groove that forms the end of the pattern is easy to make, the grooves that approach it at an angle are not. It's all too easy to accidentally run these grooves across the "end" and cut a small notch outside the edge of the pattern.