I well remember the annual audits!

Why would they poll on the sheepshank? I know how to tie it, but consider it more of a fun trick than survival knot. That question alone makes me question this survey. Now if they'd polled on the bowline or even a figure 8 I'd give them a smidge more credit.

I caught the first two hours of Longitude last night.
Fascinating movie. I will finish it tonight.

For the longitude about 4 seconds translate into a minute of arc due to the earth´s rotation. So 5 minutes of arc would translate into 20 seconds. Errors in the measuring of the elevation go on top of this.
Depending on the vessel 5 minutes of arc may the all accuracy you get with an accurate timepiece.
The calculation for cel-nav takes the known deviation of the timepiece into account. That´s why certified timepieces do not only have a maximum acceptable deviation per day but also for different orientations.

We would use our shortwave radio to receive the time tick from Boulder everyday at 1200 and then note the chronometer error.

They may be certified to some maximum error, but you still need to test them to find out what the actual error of your particular watch is (I'm calling it a "watch" here for simplicity, "chronometer" would be more technically correct).

In order to test your watch, you need a known time source, which would be missing after a grand disaster. So hopefully you tested and documented your watches error rate BEFORE the disaster. But even if you had a good watch, with a previously tested and documented error rate, you could only use that to adjust your calculations for so long. Eventually you would want to reset your watch to the known time standard again. But the known time standard is still unavailable, due to the disaster. A good watch would certainly serve you better than an el-cheapo non-certified one. But it would only serve you for so long, not indefinitely.

This is the gist of my concern in labeling CelNav "a backup for when everything has gone to heck". That may be true, as long as "everything" does not include a good time standard to reset your watch to. CelNav would be good for a while, but you would eventually need a known time standard, or a known location to reset your watch from. You would also need an almanac that contains data for a very long time. Or be a math whiz in spherical trigonometry (which most people have never even heard of) to calculate everything from scratch. The current "Long Term Almanac" goes to year 2050. Enough to cover my lifetime, but not my kids.

Long Term Almanac

While the dearth of life skills is the proverbial Elephant in the Room for the millennials (born 1981-2001), the article itself isn't much better then clickbait. There's no link to the survey, or anything representing a complete list of the questions.

As for the Sheepshank knot. That's an odd knot to test on. I've never actually used it, preferring the dog shank (pouch knot) or alpine butterfly loop. You'd be better served by testing the workhorse knots (clove hitch, square knot, figure 8 family, etc)

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The time standard would be a concern for a full TEOTWAWKI/PAW scenario. For that, you would need a sundial or some other pre-tech time keeping device to certify to, and the aforementioned math wiz (recall that the first celestial navigation tables were published in 1767, so it's far from impossible to work out the tables by hand).

But, for the general "Where the bleep am I" situation, it's not a bad skill to have. A relatively accurate watch, compass (you should have these when traveling anyway), star chart ($25), and inclinometer will let you know which direction to start rowing

I have a copy of the "Long Term Almanac". It's not a large book -- 10" x 7" and 1/4" thin.

Please! WWV is located in Fort Collins Colorado.
Please don't confuse it with that other strange town....

W and V used to be the first morse code letters radio kids would learn because WWV would ID in morse.

Lewis and Clark and Fremont had to do without WWV.

You're correct, I had forgotten....