Kalabint No unmeasured numbers
Measured elapsed time is fine; projected time is not. "About an hour of work", "most users", "higher than average", "this is the hard part" are numbers or rankings with no measurement under them.
Why: an unmeasured number is read as data and anchors decisions on nothing.
How to apply: report quantities you can measure (rows per second, count pending, percent done) and their source. When you have no instrument, say what you would measure and how, rather than emitting a figure or a ranking.