A lot of time has passed since you posted this, so my comment may be out of date. I found this post while searching for information about process smells.
I think you could improve your “better story” example. To say both “no more than” and “on average” is contradictory. If the requirement is “no more than 2 seconds,” then that’s that. There’s no “average” about it.
Maybe what you’re getting at with the “average” part is something like this: “Perceived response time must be no more than 2 seconds for 98% of interactions with the system under normal load,” where “normal load” is documented elsewhere.
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