You’re supposed to meet someone for coffee. If they’re three minutes late, no problem, but if they’re thirty minutes late, its rude. Was the change from “no problem” to “rude” a straight line, or were there steps of increasing rudeness? Do we care why? A good reason certainly increases our tolerance. Someone who is always late reduces it.
Network performance follows many of the same dynamics. We used to talk about outages, but they have become less frequent. “Slow” is the new “out.” But how slow is slow? Do we try to understand the user experience and adjust our performance monitoring to reflect it? Or is the only practical answer to just wait until someone complains?