i personally think it is unethical to shoot at a deer that you are not 99.9% sure your are going to put the arrow where you want it (within reason of course). the missing 0.1% comes from factors you can't control, such as the deer jumping the string, ect.
when i am shooting every day, i would feel more than comfortable shooting a deer at 30 yards. under perfect conditions (i.e. deer is broadside, completely relaxed, and i have all the time i need to make the shot), i would shoot 40 yards.
i practice out to 50 yards daily (when i'm not in school).