GTS here, I usually shift all gears like most everyone else, between 3-4k. A good shift doesn't necassarily mean redline, it's more so not making the car jerk when you shift it.
Since people are talking about redlining every gear while racing, where do you race, the streets? And if so, I doubt anyone has redlined their last gear because then they would be going around 130mph, and for Celicas that would take a fairly lengthy stretch.. perhaps a mile or so is my guess.
Normally I redline 3rd gear and some of 4th when getting on the highway on the way to work.
As for the last two gears I don't think anybody ever implied they redline those gears. 5th and 6th gear don't have much use when it comes to racing.