They don't do updates monthly, they do it every other month. When I had a Robin, the security update available when the update is released has been included in it.
Thanks. Good to know. Getting my wife something new in the near future and the Robin as well as the N5x are in the running. She's coming from a N5 and wants something close to that size. I was waiting to see how much the Pixel was going to cost but it's obviously in a whole different place now.