Why not .5 t,th,sat. 7 mg arimidex a week is alot more than you need and runs the chance of crashing your estrogen. I'm really sensitive to estrogen sides and that's more than enough.
You could also run bloods to see where you're at. If you're in range at .5 stay there. If you're higher than you'd like to be add in more. Bloods will tell the whole story.