Using a regulator was something a well seasoned RV'r friend told us prior to purchasing our first TT. So I've used one religiously for >7 years now at the end of the hose sandwiched between it and a brass 90 going into the TT. Never a problem.
Then it happened... this season at the Ashland, KY KOA: went out to eat and came back to a site soaked in water all over the ground. My heart sank thinking I must've forgot to valve off the TT before leaving. Thankfully that was not the case and it was nothing inside the TT. The water supply hose had burst outside near the front axle. I always carry a spare hose (they're cheap -in more ways than one) so I swapped it out all while having a
"Hello McFly" moment realizing I needed to be putting the regulator right on the CG spigot this whole time! Duh! Lesson learned.