however much that variable seems optimistic/pessimistic, it is literally a piece of junk information. It changes like a yo-yo month to month. Do a quick sort on the trackitt website database after filtering for approved 485, for TSC and sorted by approved date in descending order. You will notice that most of the recently approved cases were received by uscis in March, 2007 or later. This is just a sample, but substantially large enough sample.
For many people like me who are Asian Muslims, the picture is entirely different due to just one bottleneck-namecheck. Everything for me have been cleared and approved except NC. Everything for my wife have been cleared and approved, including NC. But since she is secodnary applicant, she is stuck with me. So far, no strategy has been proven to be able to influence/expedite NC.