The optimal number of tables that can be played at the same time is found through our own experience. But, if you evaluate your ability to pay attention and concentration, you can avoid unnecessary search and waste of money.But for many players, an increase in the number of tables leads to a deterioration in the result. There are players who are always on the lookout; no move and no stupidity of the opponent can surprise, stun, or confuse them. They may make the wrong decision, but it will be a reasonable and calculated action. I think 2-3 tables are enough.