The same way you did: draw one brick, then use the Array tool to create the rest of the plank.
Remember to set Cut Optimization to remove overlapping lines and cut the total time in half.
You could create a larger rectangular area and subtract away sections you don’t want, which might be easier than aligning separate sections. But, heck, real brick walks have weird joints, so … whatever works! 
The other way to do it, which might be faster, is to create a bitmap image, then engrave the whole thing in one shot to get a uniform exposure on both horizontal and vertical lines:
Creating the image is a bit fussier, because GIMP doesn’t have an array tool, but it wasn’t too awful.