In the kitchen
If you want the octopus to be well cooked, it is convenient that it has little water and it should be boiled what is necessary; that is, twenty minutes.
What are the so-called 'scares'? If the octopus is not tender, it has to be 'scared'. This expression refers to the fact that you have to put the octopus several times in the pot full with very hot water in order to make it tenderer. For example, it is put in the water, without letting it go, three or four times.
If you use a pressure cooker:
Defrost the octopus the night before. Leave it with salt, a bulb of garlic, full potatoes and bay. Fill the pressure cooker with water and cook it 20 minutes. If the octopus is big and you notice that it is not tender, you have to cook it once again until it is just right.