21 card 21 only possibel if you play really stupidly
So I wouldn't be surprised if you've drawn one (just kidding). Also, have you looked at Julian Braun's source code? I don't know if he ever calculated BS for 6 or 8 decks, but others certainly have, and if they did it right, they certainly did calculate all of the reasonable possible hands. This does not include a 21 card 21. (See below.) Basic strategy has also been calculated for infinite decks (believe it or not, this is easier than calculating it for a finite number of decks). Except for some composition dependant plays that only real hair-splitting geeks worry about, Basic Strategy doesn't change once you get past 4 decks (EV gets a little worse, though).
Back to the 21 card 21. The only way to do this is to draw 21 aces. Keep in mind, with the eighth Ace you have a soft 18. Correct Basic Strategy is to stop here, unless the dealer is showing 9, 10 or A. The ninth Ace gives you a soft 19. Basic Strategy is to stop here against a 9, 10 or A. Now, if you're foolish enough to believe that drawing eight or nine aces in a row means that your "personal trend" indicates that you will keep drawing Aces, the 11th Ace gives you a soft 21. Frank, I would hope that even you would be smart enough to stop here. Note that the dealer would be required to stop at the 7th Ace (the 8th Ace in an H17 game).