I've been doing full outlap-inlap stints, but the cars generally last about 5 laps in between the outlap and inlap. I'm running low on GT5 credits now though, what with re-buying all the GT cars for season 2, testing for ITCC, and whatnot.
I've been running the same tuning setup (minus any of my normal tweaks) around Grand Valley Speedway on all the cars I've tested, so that its pretty fair. I could run a stint around Daytona or Laguna, but as it stands my cars aren't broken in.
I suppose if you want us to just have the cars running their stock suspension I could revert that, but you need some tuning on the cars because otherwise certain cars will have too soft or too hard a suspension setting, and too long or too short of a gear ratio for certain tracks.
And by "people run their fastest times with the specs they use..." do you mean, "people run the cars with as close to the specs cnd researched, without tuning..." by any chance?
If you need someone to provide a "testing setup" I already have one, taking into account suspension and transmission. Any extras like LSD, Torque Diff, Aero (anything that can be adjustedthat isn't the susp. or trans.) I kept at stock.