"After feedback from design we hard-coded it to a steadily increasing bar regardless of actual progress, and the complaints all stopped immediately. "
Are you talking about progress bars, that go steadily up to 99 or 100% and then stay there, until the actual progress is done?
They can cause big frustration, too ...
The trick is to smoothly animate the filling of a random percentage of the remaining unfilled bar between, say, 30% and 70%, with the timing of the advancements themselves slightly randomized. A sort of Zeno’s progress bar. It will neither peg at 100 nor shoot past, and the pulses feel “organic”. Bonus points for advancing the bar to known fixed points of progress when real feedback is received.
Are you talking about progress bars, that go steadily up to 99 or 100% and then stay there, until the actual progress is done? They can cause big frustration, too ...