/jp/ - Otaku Culture

Did the commonly accepted way of sorting your discards change at some point?
In manga set in the 60s or earlier, you often see people sorting their discards in one long line, broken up at 12 instead of 6.
There's exceptions of course (In Akagi they discard stuff the usual 6-6-7 way, for example), but I'm wondering if this is an actual thing or if it's just coincidence.