I also supplement my Novolog usage with Novolin R due to cost factors, and because there are certain times when the longer onset, longer lasting duration of Novolin R perform better than Novolog for me.
For me at least, they do seem to be roughly similar on a unit per unit dose, but those timing factors do have to be taken into consideration both for effective food coverage, and for calculating your onboard insulin load when making subsequent doses.
I have not yet gotten to the point where I have also added Novolin N into my MDI routine, since I am still able to source an adequate supply of either Lantus or Basaglar for my daily basal shots. But I would most definitely need to start taking a good hard look at that as well, if cost concerns forced me into that direction.
It is my understanding that Novolin N can be a bit finicky/fiddly to get right, so I would probably have to have a very pressing need before I would take that route.
My current emergency backup calculations are that I could probably source enough Novolin R and Novolin N from Walmart for my daily insulin needs at a rate of around $100-150 per month if I had to. As an insulin dependent T2 with extremely high insulin resistance coupled with extremely high carb sensitivity, my daily insulin needs would be considered quite extreme by many.
Certainly my insurance company thinks so!