The problems in chronology aren't as bad when you get to a strip wherein characters age; as an example, Luann DeGroot can remember things and refer to the past without introducing the sort of absurdities one would have to deal with in other strips. The problem with her universe is that characters age at varying rates to meet whatever need Evans has at any given time. This means that Luann is eventually going to end up being classmates with Toni's niece/cousin/daughter/whatever Shannon.
It's far easier for moral lessons to stick in strips wherein people age in real time; the characters in For Better or For Worse can pretty much pinpoint when John figured out that Elly wasn't simply talking to hear herself talk when she described how overwhelmed she felt. The trouble, of course, is that since the Pattersons can not admit to making mistakes, they miss the point of what happened to them and end up getting all their lessons wrong.