Strictly speaking it hardly ever actually matters, but yeah I usually use N=8 just so I don't have to care. It should definitely be a even number so that if yo

Strictly speaking it hardly ever actually matters, but yeah I usually use N=8 just so I don't have to care. It should definitely be a even number so that if your machine layout doesn't work modulo 7 tiles (=1 wagon-length), you can group up pairs and use 14 tiles, but it might be helpful to use N=6 or N=12, and sometimes build modulo 21 tiles. (I haven't needed/tryed that so far, so I can't comment on how well it works.)