Yes, we do that too.
We have an estimate for total completion time (with a min of x seconds).
We have 16 steps that are each shown for 6% of the total estimated time.
If the job finishes early, then we rush through the remaining steps and announce it's done.
If the job takes longer than the total estimate, we show a few more "steps" that are humorous ones. These ones loop.
For example:
> Reticulating splines
> Generating witty dialogue
> Swapping time and space
https://gist.github.com/meain/6440b706a97d2dd71574769517e7ed...