actually, yes i have. 30 seconds will give no information on heat. the only possible way it will is if there is sreious friction or something wrong in the driveline.
which would cause the drivetrain to have unbelievable friction or lock up.
I don't think that 30 seconds is going to give much information on if you're running too hot or not. The sweetspot for motors is around 110 degrees F. If after a full run you are only at 90 degrees F then you should gear up because otherwise you aren't getting the full potential from your motor...