Odds of one specific edge slot:
| Rows | One edge | Either edge |
|---|---|---|
| 8 | 1 in 256 | 1 in 128 |
| 12 | 1 in 4,096 | 1 in 2,048 |
| 16 | 1 in 65,536 | 1 in 32,768 |
Every extra row halves the chance. That's why operators put their largest multipliers on 16-row boards: the edges are hit so rarely that the casino can afford to advertise them.
Example. On 16 rows, the chance of at least one edge hit in 1,000 drops is about 3%. You'd need about 22,700 drops for a 50/50 chance.