Penultimate Spots Strategy
Stealth Bomber,
Assuming you know exactly when the cut card will appear, if the count is still high as you place your bets for the final round, you should bet all seven spots, regardless of how many spots you've been playing.
Here, the card-eating effect doesn't apply (because this is the last round), and as per your posing of the question, I'm assuming in the follwing discussion that your bankroll is so large that you needn't be concerned with the covariance of your hands.
In fact, you would probably be best served by varying the number of spots you're playing on the "penultimate round" (the round before the final round) to try to ensure that the cut card will fall early in the final round rather than late in the penultimate round.
For example, say you're choosing your bets at a time when the shoe contains 10 cards before the cut card. Now you have three options.
(1) You can make this round the final round by playing all 7 spots, which will get you 7 more high-count hands. If you play 4 or more spots, this will also be the last round (and will probably be the last round if you play 3), so if you're planning to play that many, you should just play all 7.
(2) You can play just 1 hand on this penultimate round, and then play all 7 spots on the final round. This will almost certainly get you a total of 8 high-count hands... "almost certainly" because the chance of two hands consuming 10 cards is rather small, particularly with a high count.
(3) Finally, you can play 2 spots on this penultimate round, so that between your two hands and the dealer's one hand, you'll use an average of 8.1 cards (2.7 per hand). Then, play all 7 spots for the final round. If it works, this option will get you 9 more high-count hands. However, you run a high risk of hitting the cut card on the penultimate round, in which case you'll have gotten only 2 high-count hands, rather than the certain 7 of option #1 or the very likely 8 of option #2.
I would lean towards option #2 in this case, because I believe (but have not checked!) that the odds of running out on the penultimate round are less than the breakeven odds of 1 in 8.
Here's a formula you can use to calculate "S", the number of spots to play on the penultimate round:
S = INT((n-min)/2.7) - 1
Here, "n" is the number of cards remaining in front of the cut card, "min" is the target (no, not Patterson's TARGET!) number of cards that you are planning to have in front of the cut card at the start of the final round, and "2.7" is the average number of cards used by each hand... note that at high counts, this value may differ, but I have not run any sims to see what it may be. Also, the "INT" function means to chop off the decimal value of the argument, so if ((n-min)/2.7) is equal to 4.7, when you take the INTEGER, you get 4.
If S is between 1 and 7 (inclusive), then play S spots on this round and play all 7 on the final round. If S is zero or negative, then this round will in fact be the final round, so bet all 7 spots. If S is greater than 7, then play all 7 spots, then recalculate S at the start of the next round to see whether it will be the final round or the penultimate round.
"min" is "how close do you want to cut it?". If the number of cards actually used in the round is equal to 2.7 times the number of hands, then you'll have "min" cards (with a little leeway for the rounding introduced by the INT function) before the cut card for the final round. "min" has to be a positive number, but the smaller you make it, the better the chance of running out of cards on what you had hoped would be the penultimate round.
Let's walk through an example to see how this all works. Say you have 22 cards before the cut card, and you're shooting for having 5 left there to start the next round, which means "min" = 5. Then on this penultimate round you should play
S = INT((22-5)/2.7) - 1 = INT(6.3) - 1 = 6 - 1 = 5
So play 5 spots this round, then play 7 on the final round.
As for how to select "min", this seems to be an optimization problem. My gut feeling (and all A.P.'s know the value of a gut feeling!) is that the larger the value of "n", the larger the value you should select for "min". Thus, for the 10 card example, choose "min" = 3 and play one hand. However, in the 22 card case, I chose a higher "min", since the player has more opportunities to split.
Dog Hand