I have a basic gas cooker.
I always prick the potatoes, oven is pre heated at 5. Rub olive oil into the skins. Cook for about an hour.
They always come out uncooked in the middle and the rest of the potato is crumbly and dried up. The texture is so that you can't swallow it without a drink!!
I have tried, on the shelves, on a baking tray. with skewer in middle and without. I turn them. I love and cajole them!
I have never used foil, didn't think you needed to.
My friend has a lovely electric fan over and hers are bloody lovely. They retain a certain moisture!
Have tried