If I think what I have to say is pertinent, I say it. If someone has something pertinent to say to me, I want them to say it.

I get comments emailed to me (though I honestly am not always up to date with reading them, I usually get them eventually). I don't keep up with LJ at all any more, so I will randomly read back in someone's journal to the point that I am somewhat caught up, and I don't do every person every time, so it's not unusual for me to comment on a post that's a few weeks or even months old.