Six seconds a day is considered very good for a mechanical watch. Even a $10,000 mechanical watch.
If this bothers you very much, you have no choice but to wear a battery powered watch. You can not buy a perfect mechanical watch.
Once a day, pull out the crown for six seconds!
Also store your watch overnight with the crown pointing to the ceiling. This position makes a mechanical watch run more slowly. If you do this, it might only gain 3 seconds a day.
Storing a watch overnight with the crystal facing the ceiling makes a watch run faster.