I cant comment on the use of stretched tyre pressures as I don't like them but here are my reasons for my statement above.
Most of it is common knowledge and manufacturers recommendations.
The first thing to remember is that although you check the pressure when cold, the tyres will heat up as you drive and the air will expand, this will be at different rates and to different pressures. It is this pressure you will be running on, not the pressure you set them to when cold.
There are many variants to take into account when it comes to tyre pressure, these include weight, temperature, atmospheric pressure, how good is the equipment your using to inflate/check them, have you driven to a garage to check them, etc.
Manufacturers say to check the tyres once a week but most drivers dont do that.
Even if you checked every week, the change in atmospheric temperature can be sufficient to alter the tyre pressure by a couple of psi. If you checked first thing in the morning on a summers day, the temperature by the time it gets to lunchtime will change your tyre pressure, even the type of road will make a difference, a black tarmac road will absorb the heat on a sunny day and transfer to the tyre carcass more than a grey road surface.
When you check the tyres, how good is the pressure gauge, has it been damaged by the general public abuse, when was it last calibrated and how far out is it, what is the tolerance of the gauge. Again, these can all alter your pressure by a couple of psi.
Then the main one is have you driven to the garage to check them. If you are trying to get a recommended pressure then that is a big no no.
The graph below shows the rise in temperature as the car is driven, the pink/red line being the temperature of the air inside the tyre and the yellow being the temperature of the tyre carcass.
Then this graph shows the rise in tyre pressure for the same drive (please note the pressure shown is in absolute which reads approximately 1 bar higher than gauge pressure).
You can see, it doesn't take long for the temp and pressure to rise enough to make your check after the drive to the garage inaccurate.
Check your tyres when they are cold and haven't been driven on using a known good accurate pressure gauge, preferably your own.
If the weather changes the next day to be several degrees hotter or colder, your setting from the day before will be wrong.
Then theres the tyre itself, if it has a soft compound, the rubber will move around a lot more causing the tyre to get hotter when your driving and therefore changing the pressure of the tyre when it reaches its running temperature.
Little things can also change tyre temps, I have seen when testing the tyres on a car that the airflow across the tyre can alter the temp and therefore the running pressure, damaged or modified arch liners can make a difference. On your Corrado, do you still have the brake ducts as that will change the amount of airflow over your tyre.
Do you drive on motorways or round twisty roads as that will also affect how the tyre works. Do you take short journeys or long
How is your suspension set up, camber, tracking, have you got coilovers, has the weight been setup for each corner.
What gas are you using in your tyres, if your using normal air then what was the humidity of the air when you filled them, higher humidity air will expand at a slightly different rate to low humidity.
Like I say, lots of variants to take into account that all can make some difference to the running temperature/pressure of your tyres. There are many more things than all this to take into account aswell.
In my opinion, and it is only a recommendation, the best place to start for your tyre pressure is the manufacturers recommendation for that car, that will be a compromise for many different scenario's, from there keep an eye on the tyres and check for any uneven wear and adjust each tyre to suit.
For a person on any forum to say, you need to set your tyres at this pressure is still only a guesstimate and should not be taken as gospel.
I run TPMS on my car, the same one that winning team use on their F1 cars so I see how much variation I get in my tyre pressures for different journeys on different days.
Hope that makes some sense, but I know there are some that will argue my points :)