iTunes Smart Playlists: Songs not played in the last 6 hours
I do this all the time.

Create a smart playlist, Last6Hours.  Limit the size of the playlist to 6 hours; the drop down box for this setting has items, minutes, hours, Mb, etc.  Make sure Live Updating is checked.

Create another smart playlist, PlayME.  Add two items: "Playlist IS 10HourCompilation" and "Playlist IS NOT Last6Hours."  The setting for PlayME should be "all" and not "any". Make sure Live Updating is checked.

Play the PlayME playlist and you're all set.