When I write,.. I definately keep in mind how "this song" will flow into the next (in full length cd terms). That may be a good way to determine endings for other writers as well. I like to hear albums that flow,.. almost telling a story,...and or hit you hard from one to the next,...I love to use sharp endings.
I find that fade outs are used much less in modern recording. That is not to say that there is not a time and a place for a fade out. I think that they can be very effective as well.
Dave,.. you may have found week points in the endings in some of the songs posted,.. but I truly believe this is likely because beginnings and endings are often the hardest parts to structure and compose in original writing. Everything seems to have been done before.
CD,.. I like your idea of extending sep tracking,.. to potentially spark ideas. I have also been inspired by others "jam outs" at the ends of tracks. Works well.
HDA