A 2019 study* found that the health benefits of tea increased with each additional cup per day.
*Current Developments in Nutrition / June 2019
Each additional cup of tea per day was associated with 3–4% lower risk of cardiovascular (Heart) disease mortality. (Green tea risk was ~4% lower versus ~3% for black tea.)
Further, each additional cup of tea per day was associated with a 2% lower risk of all-cause mortality. (Green tea and black tea had equal effect.)