I dunno. Have been flying across large bodies of water for three decades, and my unscientific gut feel is that there are fewer cases of “bad” turbulence - perhaps because we have gotten better at identifying and avoiding them. That obviously doesn’t mean than even out-of-the-blue severe turbulence without warning isn’t always a possibility. And so I do keep the seat belt on and tight when I am in my seat. But I am not afraid for my life when I get up to stretch or to get something out of the bin or to go use the lav. The latter nowadays (increase in age) is more frequently than when I was younger. I used to always pick window seats as I like the view - nowadays for longer flights I choose the aisle seat for the ability to get up.