Comparison of sequence repetition rates

This is a comparison of repeated sequences in both the 408 and 340 ciphers.

Note: I am using the Webtoy's transcription scheme.

These sequences are derived from reading the cipher as normal text (from left to right, top to bottom).

4-grams
No repeats exist in either cipher for n-grams where n is greater than 4.

N-grams, in multiple rotations and mirrored arrangements
This n-gram analysis was performed upon various rotations. First, the cipher is rotated 0 and 90 degrees clockwise. Each resulting ciphertext's repeated n-grams are tallied. For the second part of the analysis, the cipher is first flipped horizontally, and then rotated 0 and 90 degrees clockwise. The resulting ciphertext's repeated n-grams are again tallied.

Rotations to 180 and 270 degrees are excluded for brevity, because the repeated n-gram counts are identical to the 0 and 90 degree cases, respectively.

Maximum non-zero repeated n-gram counts are in boldface for each combination of cipher and value of N.

Observations: Remaining questions:
 * The maximum numbers of repeated digrams and trigrams occur for the original 408 cipher, when it is unaltered by flips and rotations.
 * However, the maximum number of repeated digrams occurs for the 340 cipher when it is flipped horizontally.
 * Also, the 340 cipher's repeated trigram count is unchanged by the horizontal flip.
 * What is the significance of the increase in the maximum number of repeated digrams when the 340 cipher is flipped horizontally?
 * Experiment: Using the known 408 key, generate random encipherments to fill the 408's cipher block with encipherments of random sentences. Then, count the number of times that the encipherment of a random sentence results in ciphertext arrangements that produce maximum repeated digram counts when the ciphertext is rotated and/or flipped.