Well, for my two cents:

In the past, I've religiously folded (flaked) my sails. Over time I've noticed the material wears, weakens and tear along the "fold lines".

More recently I ensure the sail is completely dry and I use a stuff sack for "between use" storage. Since this change, I've not experienced the wear, weakening and eventual tearing along the fold lines. That is probably because the fold lines are random, when using the stuff sack.

Wow, look outside, it's Spring and time to get the boat ready for the season....waaa hoooo...!