Paul -- you are right, DON'T try this.
Don't even start. Although based on the techniques you already use to stay focused, it would be right up your alley.
So here are 3 consecutive nights of OCD fails (Plummy, avert your eyes now) in the name of experimentation. Went for time on the Dec 9 and 11 rows, Dec 10 was a distance row. Based on what the PM was displaying during the row, splits appeared more stable on the distance row, but not true -- so I agree with your analysis Paul that it's much harder to succeed. So now my question is: can I optimize my chances by picking an optimal pace/500m? My target tonight on the Dec 11 row was 2:18.2; however, at the bottom of the first 13:00 split, I saw it flash from 2:18.2 to 2:18.1 at the last moment, so I knew I had to target that split for the remainder. I'd have to have stayed closer to the 2:18.2 however, to have avoided the two 2:18.0's. It also appears the 2:20 pace was a better choice for getting the # of meters consistent.
