Hi DJD,
Yes the AutoDJ feature will never interrupt a song mid-track and will always play to completion. So if a 7 minute track started just before a scheduled playlist was due to start it would play for the full 7 minutes before it then starts the playlist. So with this in mind you need to build your other playlists total running times around this. So for example, try and create playlists with total running times that are in hour blocks.