Remember that in different iterations, these very same engines were designed to run on 5 quarts. Perhaps even less…
Like was said, I’ve never seen a Windsor pan that held 7 quarts. But the larger capacity pans, such as the 6 quart bronco and 4wd pickup pans were designed with the extra capacity for engines that might see severe duty.
Not severe as in racing, but severe as in working hard, pulling heavy loads, sitting on hilly terrain for extended periods, etc.
Mustangs and other cars with 5 quart capacity pans were, I’m sure, raced extensively even without the custom race pans with higher capacities.
Another good Engine Masters watch is their story on free horsepower through oil or something like that.
They kept reducing the capacity in the pans, even the big race pans, and gained power at maximum RPMs with less oil.
Granted that doesn’t necessarily equate to our use and our need for power and that last 3 hp at the top end. But it does indicate that you can rev your engine to 6000 RPM and not starve it for oil.
Even if it’s only got 5 quarts total in it.