I think you need to do full 30 minute session to get .07 points.
That's not quite true, the actual SR gain is dependent on two things, number of corners and incidences.
A three turn track like Daytona would be about 110 corners giver or take a few. A short
track like Lanier would be around 450 corners, again give or take. Assuming you had the
same incidences in each, Lanier would net your more SR. The same could be said for a road
course as well. Granted the longer you do a Time Trial the more likelihood of significant
gains.
Your also dealing with a 1000-2500 corner history, if you push out a bad SR race with
good SR you will see a greater gain verses pushing out a good SR event with another
good SR event.
Clear as mud...
Strip