Here are some facts about Friday's T-trade.
Friday Dec 08, 2017 volume 88,595,300 million . T-trade 15.3 million Fact.
Friday Dec 01, 2017 volume 7,768,700 million. T-trade 1.6 million Fact.
Friday Nov 24, 2017 volume 20,537,200 million. T-trade 7.8 million Fact.
I find your statement weird that ''In fact, there have been several Fridays without T-trades for some reason''?
Most likely that OS has maxed at 900 million.
If that is a fact, the stock would fly next week.