My grandmother always swore that tea only tasted at its best at, or near, sea level and she never washed her tea(or coffee) pot, throughout her married life.
Common wisdom is: It should be made with freshly drawn, freshly boiled water and left to brew for at least 6 minutes. It used to be said that tea bags were made out of the dust and residue, but I think that those days are past, I held on to leaf tea and a strainer until about five years ago.
However my tea making is very straightforward