Here is the result of a scrolling experiment.
Here is the 340. X axis is the leftmost column ( 1 means undisturbed message, 17 means 17th column shifted to the leftmost position, etc. ). Y axis is the count of cells highlighted because they are part of a period 19 repeat. For the 340, Y varies between about 100 to 120.
matrix.discussion.4.png
I LIKE KILLING using Jarlve's first matrix. Y varies between about 100 to 120.
11 5 7 12 13 50 40 58 22 28 1 14 2 23 3 10 39
3 46 33 51 15 57 24 45 52 18 61 25 42 43 9 52 34
22 62 44 26 47 48 6 1 9 11 28 35 44 27 52 60 51
12 49 36 33 1 8 13 14 15 30 22 52 31 23 53 11 46
56 12 19 40 54 55 42 41 56 45 11 46 37 51 3 28 29
30 31 4 5 34 32 16 40 35 44 24 45 43 61 13 14 17
6 39 25 11 20 14 23 11 21 62 22 44 18 40 41 33 20
12 59 36 11 26 58 25 21 28 20 7 13 37 54 18 16 14
15 43 32 50 11 2 34 55 11 53 31 53 55 57 45 40 35
61 11 21 18 39 2 56 33 3 40 20 30 11 48 32 22 41
18 5 18 21 51 36 8 20 13 23 21 62 51 45 45 24 38
37 49 52 14 34 53 35 25 15 50 47 36 51 15 28 11 20
19 52 4 47 39 45 22 14 23 11 6 48 24 1 37 49 28
55 2 3 51 33 25 34 13 50 32 14 29 30 11 51 47 55
55 17 4 9 21 49 15 52 31 5 53 40 33 22 31 50 23
25 11 41 12 7 35 51 38 48 11 29 30 14 49 4 27 23
14 59 17 7 45 44 15 2 25 32 55 11 23 30 18 31 19
11 9 26 10 41 37 12 40 6 13 58 14 3 47 59 23 37
58 4 25 28 11 15 52 15 18 33 12 7 17 21 8 55 23
1 47 23 21 27 24 29 30 45 44 36 48 32 25 16 53 13
matrix.discussion.5.png
I LIKE KILLING using route transposition with an 18 x 19 inscription rectangle. Y varies between about 80 to 120. Scrolling disturbed a lot of the repeats.
24 5 54 23 11 24 1 38 32 12 50 26 13 20 44 51 6
28 13 29 13 34 30 16 47 35 33 39 34 21 47 48 11 37
20 12 34 8 25 8 11 31 38 52 22 13 49 7 2 41 53
35 23 14 8 38 3 27 1 50 24 45 21 32 51 52 15 37
17 42 25 37 24 39 53 55 11 54 23 34 45 12 1 20 50
23 18 16 2 9 42 21 33 19 46 26 48 48 18 13 32 11
24 20 51 14 58 44 22 1 4 15 11 12 22 12 33 59 49
40 41 35 44 23 52 24 52 13 45 56 32 57 61 28 25 38
23 50 47 17 19 22 47 51 52 39 23 1 14 62 15 40 29
50 44 11 5 50 2 18 31 11 24 20 16 58 10 27 48 61
55 25 11 12 9 15 10 11 22 28 56 36 3 23 24 25 11
29 41 59 37 49 17 19 7 4 30 57 22 11 18 19 51 31
8 31 4 54 23 19 49 55 3 3 34 53 11 35 36 62 22
25 28 11 29 56 33 30 42 38 36 32 54 19 39 47 18 6
40 44 48 5 4 12 13 61 31 14 33 53 15 49 11 26 33
14 13 55 11 50 14 34 9 46 35 52 41 54 20 11 15 45
22 11 60 52 45 53 21 44 10 59 23 4 45 43 7 2 36
32 40 28 50 42 50 44 20 1 12 3 24 59 33 62 31 21
37 52 1 55 30 20 13 14 39 15 50 6 31 11 25 11 5
12 16 27 21 34 49 48 13 44 44 8 6 58 41 28 29 29
matrix.discussion.6.png
It seems as though the 340 behaves more like your matrix than route transposition, Jarlve.
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