Spoilboard grid for odd size

I’m running a Longer Ray 5 20w with a 375x375mm work area, and I’d like to setup a spoil board grid for repeating jobs like this:

Easy spoil board setup

The video uses a 10mm grid, would the easiest solution for me be to switch to a 5x5 or 15x15mm grid in Lightburn? It seems like using a 10x10 and offsetting the whole thing 5mm on the edges would be weird