The bottom-triangle row-count conjecture for chip-firing configurations

A configuration $F(x,y)$ consists of rows of chips, with the bottom triangle formed by the minimal rows at the bottom of the configuration. Let the longest row be a row having maximal length among all rows in the configuration. Bottom-triangle row-count conjecture. The number of rows in the bottom triangle equals the length of the longest row minus $1$. This is motivated by computations of $F(x,y)$ for $n$ up to and including $12$, which show that the intermediate configuration ends with a long rectangle followed by the bottom triangle, with the rectangle as its widest part. The claim remains conjectural beyond these computations.