A countdown is a surefire way to build tension. Any time one starts, the pulse quickens—what happens when we get to zero? Sometimes movies shortcut to it, flashing between other scenes to keep things moving faster or doing the same for the opposite effect, slowing down the final 10 seconds by cutting between people interminably. Films use countdowns to make you stew in the tension, anticipating the explosion of excitement or total sense of deflation that is the inevitable result of numbers slowly decreasing.
Let’s revisit some, shall we?
The best reading is Bill & Ted’s Excellent Adventure, obviously. Video creator ThorC1138’s rules for constructing the supercut were to use 100 unique films and not use any years as numbers. He cites as inspiration another countdown from a few years ago which you can view below, but, fair warning, that one starts at 50, and so does not have a chance to use the Bill & Ted’s Excellent Adventure quote, thereby making it inferior.