Know the Oddsspinner · Roulette strategy lab

What breaks it: American wheel, long sessions and table minimums

The gain survives other seeds and a bigger bankroll, but long sessions, $25 table minimums and, for wide layouts, the double-zero wheel break the ladders; only the cash-out version shrugs off length and the wheel.

Chapter 8 of the spinner roulette research (chapters 0 to 9): What breaks it.

We re-ran the survivors under each change. Other seeds moved the typical session by at most $19. A $10,000 bankroll and the la partage rule changed nothing. The American wheel’s extra zero costs 3 to 8 points of chance of ending ahead; b3 and c9 stay ahead, the widening a1 drops to −$1,978. At 1,000 spins every ladder without a cash-out ends negative.

The c9 cash-out shrugs most of this off: every session stops by spin 250, so length does not touch it, and on the American wheel it keeps +$286 and 88.7 %. At $25 table minimums nothing works: comparable ladders lost the ladder in 90 % to 100 % of sessions. Every average is negative.

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The numbers

Typical session / average, by strategy under each change
StrategyEuropean, 500 spinsAmerican wheel250 spins1,000 spins$10,000 bankroll
Flat $25 on red-$350 / -$338.21-$650 / -$653.14-$150 / -$170.85-$650 / -$675.80-$350 / -$338.21
b3: two streets, stacked+$1,679 / -$320.90+$1,594 / -$520.74+$862 / -$166.99-$1,947 / -$474.46+$1,679 / -$320.90
c9: streets to 12, stacked+$1,540 / -$295.45+$1,497 / -$535.24+$777 / -$156.42-$2,126.50 / -$472.93+$1,540 / -$295.45
a1: streets, widening+$1,494 / -$330.93-$1,978 / -$699.60+$775 / -$190.84-$1,568 / -$538.08+$1,494 / -$330.93
Cash-out versions of c9 and a1 under each change
StrategyTypical sessionChance of ending aheadAverageWorst 5 %
c9 + cash-out, European, 500 spins+$28690.3%-$46.25-$3,210.44
c9 + cash-out, American wheel+$28688.7%-$100.32-$3,219.87
c9 + cash-out, 250 spins+$28690.3%-$46.25-$3,210.44
c9 + cash-out, 1,000 spins+$28690.3%-$46.25-$3,210.44
c9 + cash-out, American wheel, 1,000 spins+$28688.7%-$100.32-$3,219.87
a1 + $226 cash-out, full ladder+$23291.7%-$63.55-$3,380.37
a1 without its last level + $226 cash-out+$23072.4%-$38.08-$840.80
a1 without its last level, no cash-out-$36030.6%-$124.31-$840.80

Takeaways

The math

American wheel: p(k) = c(k)/38 and the edge is 2/38 = 5.26 %; realized −5.43 % (b3), −4.91 % (c9), −5.47 % (a1), −5.23 % (flat red). q grows by Π (1 − c(k)/38) / (1 − c(k)/37) over the levels: b3 0.00591 → 0.00685, predicted P(no cap) 0.58, measured 0.585; a1 predicted 0.49, measured 0.473, below ½, so its median flips. The c9 cash-out: q_SL 0.00510 × 1.181 = 0.00602, (1 − q)^20 = 0.886, measured 0.887; mean −$100.32 (−4.75 % of $2,113).

Length: P(no cap at S) = e^(−k·p·S/B) falls below ½ at S½ = ln 2 × B/(k·p); at 1,000 spins the medians stay ahead until 690, 860, 570 (b3, c9, a1) against n½ 723, 874, 577. La partage halves the edge on even money only: flat red −1.36 %, mean −$169.82. With onCap stop the cap loss ($3,444 to $4,919) stays under $5,000, so extra bankroll is never used. Default table ($25 minimums): a9, b11, c6 kept 0.3 %, 9.8 % and 0 % of 2,000 sessions uncapped.

edge (American) = −2/38 = −5.26 %
q(American) = q × Π (1 − c(k)/38) / (1 − c(k)/37)
S½ = ln 2 × B / (k·p)

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