I use the lock; it's there for a purpose, so I take advantage of it. Ordinarily, I don't worry so much about the blade closing when using the knife for cutting things. But on occasion, when I've been stropping the blade to keep it tuned up, the blade will sometimes try to pivot closed while doing so. So I just lock the blade by habit, every time I pick it up. I've noticed this closing tendency on the strop with some conventional slipjoint knives too, if the backspring tension keeping the blade open is a little less-than-strong.
Others' earlier mention of using the lock 'open or closed' is a good point. I'm actually more concerned about the blade partially opening in-pocket, which is obviously dangerous with any knife. So with mine, it's always locked when I carry it in-pocket.