I agree Chris, with some hitches it is obvious when hitched and locked. My first hitch was a slide bar, with rotating handle that would not reopen against a spring load. It also locked. I never heard of a pull test back then, but it was a good policy to look closely to see the bar behind the proper portion of the pin.
Now with a dual jaw wrapped around the pin, same setup as yours, it made me wonder if somehow those jaws could spread and open on their own. New truck, new hitch, I did pull test as per owners manual, first time. I later looked the hitch over carefully, while moving the arm. I could then see, there is no way jaws can open with the arm closed and pinned, without destroying the hitch head. I still look closely when hitching, and look once more before getting in truck to pull out, but no pull test.
This is just my experience, and I won't tell anyone not to do a pull test, especially a new FW owner. You have to do what makes you comfortable, newbie, or pro!
Jerry