We used a Treg hitch for 20 years, and like you, at times it needed a bit of effort to remove, but certainly doable.
Twice it was near impossible to get the pin out, the first due to the weird angle I had to back the trailer in on and then couldn't get all the weight off the pin. I ended up taking the pin out of the gooseneck and driving off. I then undid the Treg pin easily and replaced the tow hitch back in the receiver on the truck.
The second was after doing a couple of weeks on gravel roads without unhitching and found that fine gravel had fallen in around the pin making it very hard to remove. I ended up spraying WD40 down around the pin, let it sit for a while, then after removing the locking D clip, spun the pin around in a circular motion, listening to the grinding noises. I then rotated the hitch 180 degrees and gave the pin some love taps with a rubber mallet. It came out pretty easily, and then after a good wipe down, all was good. It did teach me to take the pin out every few days when camping off road and not unhitching, which I did by locking on the handbrake and just lifting out the pin, no effort at all.
I liked the Treg as a hitch although the new trailer runs a DO-35, which has it's own peculiarities.