Factory ammeter

I think you're correct. The surface area of the contact is important for good electrical flow. Also the terminal is thin relative to a 10 or even a 12 gage wire.
Its where I often see heating when subject to long periods of high current.
Notice the heating metled away the moisture seal around the crimp. I beleive this terminal saw 25 to 40 amps for 20 to 30 minutes.
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Above is the R6 wire. Below is the Fusible link. Again the heat build up is at the crimp. The damage is not quite as bad, probably because it didn't see as much current, and possibly because the crimp was better made or the terminal a little better quality.
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Of note is these same terminals on this car's original '67 harness don't show this damage. This happened under my watch, not the first 150 or 250,000 miles. (Mostly because I left the parking lights on in a remote location)

A couple of more from this car. These are wires from the key switch connector.
My guess is the accessory feed saw additional current loads from the aftermarket A/C unit that was added to the car in the late 60s or early 70s.
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One more. Headlight power into the switch. Looks like the highest resistance here was the terminal contact.
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And of course there is an example a couple pages ago in this thread showing the damage to terminals that saw over 40 amps through them for over 20 minutes.
It's actually impressive how well they did.
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