Did anyone playing AD&D use the ability score adjustments on page 13 of the DMG for character aging? We never did, because we never really played long enough for the character to age. They also described a process where there was a lot of adding and subtracting and it just didn't seem all that straight forward. Looking at it again, if you did all the math ahead of time for each age bracket this might be interesting options for B/X D&D players who make 3d6 (or 4d6) in order characters. By choosing the age of your starting character you can adjust their ability scores.
There'd certainly be an incentive to play a middle-aged or older Cleric or Wizard -- which is more in keeping with certain fantasy fiction.