It used to be the TV networks would save their biggest hit series for 10 PM, the end of primetime. Shows like "ER," "L.A. Law" and even "Law & Order" all finished off the night for years. But now analysts are suggesting there's a new golden hour on network TV - 8 o'clock. Which is why you may see more and more of their bigger series starting earlier in the night than ever before. 

DVRs and streaming have obsoleted a lot of this, of course, but it's still interesting to contemplate how much has changed. 

Broadcast Schedule’s New Paradigm: How 8 PM Became “The Best Time Period On TV For Live Viewing” As 10 PM Hangs In (For Now)