According to one of the articles on my HEM, they found that people that are 3betting between 5.2% and 6.2% have the highest median bb/100, and the higher 3bet percentages were still quite profitable.

For 6max, I would experiment with 3betting MP or CO openers with hands like AQ, KQs, AJs. You can also usually 3bet most Axs hands against tighter players to take down the pot preflop, or to take it down on the flop with a 2/3rds size bet. This will also help you get better value out of QQ+.

FWIW, my 3bet % was 5.5% this month and 6.3% last month. Don't go crazy with it though, and use it against the right types of players.

Positional stats would be helpful too to help us give a better picture. PM me if you want to swap some hand histories.