I've considered getting a turbo cool down timer.
Once every couple of weeks, I have to drive up some twisty roads at high altitude. 9-10,000 ft. Even though I am only going 45mph, unloaded, it will take at least 5 minutes for the turbo to cool down to 350. Even in the dead of winter!
Under "normal" conditions, I agree, the turbo cool down timer is not really necessary.
I have the Practical Solutions high idler and it works great. I got it after I got tired of fooling with the Stick and Seat method. But I don't really use it as much as I thought I would. When it's cold out (20f or less), if I am trying to warm things up faster, the high idle seems to worsen the quantities of nasty smelly white smoke.
Another interesting feature of the P. S. High Idler... If you leave it on and try to drive, it acts like a valet switch. Full throttle is like half throttle.