yeah man, i think maybe you're thinking about this in the wrong light, as it were.
what i mean is that you maybe should focus more on providing an optimal environment for your plants and less on what things cost, personally, i would run my veg lights 24/7 unless the growth was too vigorous for my flower op to support., after all, more light equal more bud, or so they say.
...sometimes you can get lost in the weeds thinking about details bra, you'll never get things perfect so learning to relax is essential.
...so maybe forget trying to figure out how to save pennies and remember that you are growing dollars, learn how to grow more of them and the pennies will take care of themselves.
peace, bozo