I think most feel it's much better to do it in multiples of two. Double the quantities of everything to get a double portion. Do this twice for 4, 3 times for 6, etc.
I think going any larger than a double portion, doesn't work proportionally, and won't get as good results. You won't get enough heat from a home cooker to cook things properly/BIR method for large portions.
That's what I do, anway.
