When does coincidence stop feeling like coincidence?

I keep coming back to this question because it sounds simple, but it isn't really. Like, if you think of someone and they message you five minutes later, once is nothing. Twice is probably still nothing. But after a while some people start feeling like there is a pattern. Curious where people draw the line. Is it the timing, the emotional feeling, how specific it was, or just the amount of times it happens?