16 flights is extremely unlikely. Starship payload to orbit is ~150 tons , so max of 8 to fill 1200 ton tanks of lunar Starship.

Without flaps & heat shield, Starship is much lighter. Lunar landing legs don’t add much (1/6 gravity). May only need 1/2 full, ie 4 tanker flights.

— Elon Musk (@elonmusk) August 11, 2021