I'd say, for running text, wrap somewhere before
80 characters per line
(preferably before about 78, since some programs lose a column or two
on display - personally, I wrap at column 72). I'm sure others will
differ in various details, but I suspect most will probably be
somewhere close to that.
If you don't wrap by 72, then there won't be room on the card for
serial number, and it will be hard to reassemble a dropped deck.