hi I've found a few posts about this but not what I need, so 
We are using Myriad 4 on a separate PC as a 24hr sustaining service for non-live broadcast hours. 
Live Presenters dont interactive with the PC, they just need to fade it the PC up at the right time to make the transition. 

Myriad doesnt always start the TOH hour at the right time, sometimes letting it play the full set of scheduled songs from that hour. 
(eg 8-9am will have 1h10 max and myriad plays it all before beginning 9-10am) 

We are struggling to understand why? or how to fix it.  
We think it might be the Absolute Time markers in clocks. Our clocks have them as the very last line with a time of 59:59:59, 
As this is the last line, we usually over schedule some clocks to avoid dead air at the end of the hour, - The clock builder will say that the Absolute time is at 01:10:15. (1h10min in)  BUTIf i try to get this as close to the end of the hour, then that hour will never have enough songs.  

We think this extra 10-15mins are adding up and sending our sustaining service off by a few hours by the time (recorded) breakfast is supposed to be on.  However in demo video, they use markers at 00:00:00. 

Should we use both?  one not the other? or none at all?
Log is always set as On and AutoFace

Any help on this will be most grateful.  

Ben