I experience intense moments of deja vu probably 2-3 times a year. I'm 90% sure it's connected to dreams for me, because even on one occasion, waking up, I made the mental note "remember this intensely specific dream, and see if you get deja vu", and I actually did, in the middle of a presentation. I'm guessing it's because when dreaming my mind goes through a vast volume of possible scenarios, so statistically I'm bound to encounter something that it's internally 'rehearsed.' Maybe I sleep too much though, perils of freelancing.