SLF here. I have never experienced severe turbulance, thank heavens. Worst experience was on an Air Canada L1011 coming into Calgary in a thunderstorm in the early 80s. We were the second last flight before they closed the airport. Was with my dad and it was like a roller coaster without knowing what was coming next. My father, who flew several times a month for business, was calm, so I was too. Years later talked with dad and he said it was the second scariest aviation experience he had (the first was an aborted takeoff).