Why are three-dimensional models useful for understanding the lunar phases?

Because if the Earth was flat it would stop 99 percent of the suns light from getting through.

Three dimensional models are useful because the face of the moon that catches the light of the Sun depending on their position at any given time could be depicted well. Circular models would be the best visuals for the lunar phases.

some sources quote the lethal dose, for an average 170lbs opiate-naive individual is between 75 and 375 mg