Turnable database with TimeLine

I think the confusion lies in trying to use the Timeline, which shows average speed over any period of time, to evaluate momentary, micro-variations in speed due to stylus drag. The timeline can only infer that speed is varying once the stylus is in the groove if the laser mark drifts. The problem is you can't know if the drift is due to speed being something other than 33 1/3 exactly or if speed is actually changing during play. The only sure way to measure the effects of stylus drag on speed for a particular tt is with a very fine tachometer.
Think of driving your car. You time yourself from point A to B and knowing the distance determine your speed. That is average speed. If you want your speed to be exactly 30 mph then you must leave and arrive within a specific time interval. The thing is, you don't know what your speed variation is between points A and B. In order to know your speed variation you must watch your speedometer. The speedometer is giving you instantaneous speed. Showing your stopwatch to someone as proof that you drove exactly 30 mph between A and B doesn't prove that your speed was a constant 30 mph. Maybe you went up a hill and dropped to 25 and then down a hill and got up to 35 for a moment averaging out to 30.
The timeline is like a stopwatch giving you average speed.

Agree with Tonywinsc. I think the KAB measurement makes more sense for average speed and constancy of speed.

I disagree. The Timeline measures the speed accuracy AND constancy with each rotation of the platter. How much more do you want or need? I understand Tonywinsc's point as a matter of theoretical discussion and extreme obsession, but if constant speed with each rotation of the platter is not enough for a person, I suggest that he needs to find another hobby altogether or perhaps listen to digital only.

Lew,
If you watch my video of the Raven AC-2 with the Timeline.....you can see exactly what you suggest albeit in reverse.
You can witness the Timeline laser moving incrementally to the left as the record is playing.....whilst when the tonearm is lifted.....the laser is stationary.
This means that the turntable is spinning exactly at 33.33rpm without stylus drag....but runs slightly slower WITH stylus drag.

Actusreus,

If a turntable slows down for a very brief moment due to the stylus drag and the Timeline registers it by shifting the laser spot but then remains constant, how relevant is that drag save for the very brief moment of the stylus settling in the grooves and the turntable adjusting its speed?

I have never witnessed what you describe.
Stylus drag is constant (but variable if you know what I mean)....so that when it slows down the speed of a turntable platter......that speed is changed for the duration.
It doesn't 'spring back' to accurate speed after the initial 'shock'....although with some direct drive turntables using speed-error correction.....this might be a possibility.
I just haven't seen evidence of it using the Timeline?