Then I'd say that was the root cause of the failure -- not checking something due to a misplaced sense of urgency. She should have realized that that there was no pressing need to land, so she could take the time to check TPA and other significant airport data in the A/FD even if that meant circling clear of the airport traffic pattern (vertically or horizontally) while she did.
How about runway obstruction data? Or actual landing distance available for all runways? Or any of a bunch of other equally important information? That's why they put all that in the A/FD, and why they expect pilots to refer to that document (in either paper or electronic form) before landing somewhere unfamiliar.
In most cases, nonstandard TPA's are driven by airspace (e.g., the low patterns at Freeway W00 to stay under the B-space) or other procedural issues. There are just too many possible issues to have one regulatory TPA height with no exceptions. However, I realize that there are some airports where the local TPA was "standardized" at 800 AGL back when that was the AIM recommendation (as it was when I started flying in 1969), and they stuck with it for no particular reason when the FAA changed that recommendation back in the 70's. In other cases, they just wanted round numbers in MSL, and so did something like 1000 MSL at an airport with a 42 MSL elevation, eating the 958 AGL TPA height as a cost of convenience.
All that's fine as long as they get it properly published in the A/FD, and pilots don't use unofficial sources for deciding what TPA to fly. But airplanes descending on one another due to someone flying an 800 AGL pattern underneath someone else flying a 1000 AGL pattern is a known cause of midair collisions. We instructors need to do what we can to prevent that from happening by teaching everyone to use the official A/FD rather than other unofficial sources so we're all singing out of the same hymnal.