No. You are still not getting it. The maximum number of years worth of past damages any patent owner is permitted to claim is 6 years.
If a patent owner sues for infringement anywhere during years 1-6, then they can claim all past years plus all remaining years for future royalties, for a total of 20 years of monetization.
If the suit is filed in year 7, they can only claim 6 years of past damages, meaning year 1 is now lost and unrecoverable. Years 2-7 are eligible for past damages and the remaining 13 years are eligible for future royalties, for a total of 19 years of monetization.
If the suit is filed in year 14, they can only claim 6 years of past damages, meaning years 1-8 are now lost and unrecoverable. Years 9-14 are eligible for past damages and the remaining 6 years are eligible for future royalties, for a total of 12 years of monetization.
If the suit is filed in year 20, they can only claim 6 years of past damages, meaning years 1-14 are now lost and unrecoverable. Years 15-20 are eligiblefor past damages and no future years remain on the life of the patents, for a total of 6 years of monetization.
If the suit is filed in year 23, they can only claim 6 years of past damages, but only 3 of those years (years 18-20) are recoverable since the patents expired following year 20 and no damages can be claimed for years 21-23. In this scenario, there is only 3 years of monetization.