dave -- your system is not all that much different from some of the old methods of calculating exposure used before guys invented light meters -- I've got some in my collection, small books that go at great detail into sun, subject, time of day, time of season, etc etc etc.

It all boils down to being aware of your film, your equipment and your surroundings ... if your system does this for you, then good on you, ignore those who say you over-complicate things. I personally like light meters but consider them advisory only -- final subject assessment is done in that greatest of all micro-processors, the human brain.