A small experiment
Why does 99%
take so long?
Same work. Same ten seconds. Two very different promises.
A progress bar can count finished tasks without knowing how much work is left. If the last task is much bigger than the others, 99 out of 100 can still mean a long wait.
99 small tasks. One slow final task.
Possible here because we set the task sizes ourselves.
Both bars will finish together.
A percentage needs a denominator.
Files, bytes and finished steps are different things to count. A hundred small files and one large file make this obvious: most of the files can be done while most of the data is still waiting.
This example gives the first 99 tasks equal, small shares of the work. The slider decides how much belongs to the last task. Both indicators watch the very same ten-second job; moving the slider changes their shape, not the finishing time.
So what would be more helpful?
Sometimes a label such as “checking the download” says more than an overconfident countdown. In this little model we know the workload in advance. Real software may discover more work halfway through, or wait for something it cannot predict.
The experiment runs entirely in your browser. It does not test your connection or time any real download.