If you enjoy that kind of stuff, then go for it. I do wonder with all the variables on the road how accurate it is. If you want to get really 'accurate' it would be interesting to see a meter that gives an accurate reading of the amount of flow from the tank in real time and a cumulative amount of fuel used from the time of fill up. Then you could have a better idea of the running mpg and adjust your drive for maximum benefit.
Or you could fill up when you get between 1/2 and 1/4 tank like so many of us who can hardly spell spread sheet.