Well, I don't know about "maximum" bets, but you'll see a favorable count about 15% or 20% of the time. The rest of the time, you'll either be backcounting or betting minimums.
That will depend entirely on the level of penetration. The deeper the pen, the more positive counts you'll see. As Mike said, you will see a positive count about 15-25% of the time, and a max bet may only be 3-4%.
According to the KO Blackjack book, you make your max bets at the pivot point which indicates an advantage of 2% (page 106). Using the chart in Arnold Snyder's Blackbelt in Blackjack on page 177, I believe you will encounter a 2% or greater advantage approximately 5.5% of the time in a 6D game with 75% penetration. I hope that helps.