The worst is the attempt to make a smooth progress bar that is a complete and utter lie. Don't want it to jump ahead and back? Don't want it to pause for long periods of time? Just calculate a function of the elapsed time that approaches, but never reaches, 1. Something like 1/x will give you a proportion that starts at 0 and approaches 1, getting slower and slower as it gets there. This creates the Zeno's Dichotomy paradox where the closer it gets, the slower it gets, so that you never actually get there.