In my view, it depends on what your kiln configuration is, what is in the kiln (thickness/size/importance), and the characteristics of your kiln.
My smaller kiln 500x500mm I control to 100C, while the big one 1000x2030mm I control to 100C, but routinely pull the 3 plugs from it at 200, and crack open at 150C. If I don't do that, it takes more than 24 hours to cool from 250C to 30C. Of course both these kilns are clamshell types - top loaders have different characteristics, especially with the lid open. The position of the glass within the kiln has an effect on what you can do in cooling too.
Keeping the controller on down to relatively low temperatures warns me when I have opened the lid too much. I can hear the relays kick in as the kiln supplies more heat, as the chamber is cooling faster than I programmed, so I lower the lid a bit.
You will learn by cracking when you are cooling too fast. As is said by many "speed kills".
You must be in the southern hemisphere to have 40C at the moment.