vladasyn
My understanding is that any MIDI data on a track would create a clip disregarding of what data it is. If I use Mod wheel or CC or PG or a pedal, it creates preview on a track. All tracks appear empty- there is no microscopic events hiding somewhere at the end- I dont think it would require zoom to see if something was there- it would be visible on a track, wouldn't it.

A single CC/program change command will indeed create a clip. MIDI clips however are the size of their contents. If that CC is a single isolated instance without any notes present that clip can be tiny, maybe a 1/64th note or smaller, which occupies a minute vertical line in track view even when zoomed. Wven if there is a note, again the clip might only be the length of the note, which if it's short enough again "disappears" in track view.

Which is where the event view comes in handy for spotting things like this.

As soon as I add an automation envelope, I go to the end of the song an use the razor tool to kill the last dot.  One reason is the problem above.  Another reason is that if I add a node I want the volume at that node: I don't want the node to be the beginning of a slope to the end.
 
A related problem: sometimes I have clips that look blank but go way beyond the end of the song and I don't seem to be able to split and delete.  I'll take some screen shots the next time that happens.