This reminds me of the many articles stating that pirates didn't wear eye-patches to cover up an injury but that they used them for for their eyes to adjust to

This reminds me of the many articles stating that pirates didn't wear eye-patches to cover up an injury but that they used them for for their eyes to adjust to the dark when entering a ships hold. Even though there's more evidence that eye injuries were probably just common across pirates. Applying Okkam's razor I'd conclude that most medieval staircases were probably build clockwise simply because most staircases were already built clockwise.