This is one of the more interesting discussions on this forum in a long time. The frequency of water line failures and the reasons for them in our RV's is very broad, but certainly important information.
I'm in the pool who knows better but doesn't shut off the water. Probably the best and easiest solution is to fill the fresh water tank and use the pump religiously, while shutting the pump off when not needed. Free advice which I haven't heeded.
We were parked in the infield at Daytona Speedway this past February and experienced a water line blowout. Fortunately we were there at the time and shut the water supply down quickly, but still had plenty of water under the cabinets in the kitchen as well as the bays below. In our case the break was at least partially my fault since we had a drip at the hose connection in the utility bay that I couldn't get stopped with all the usual fixes and it irritated me to the point I went and purchased a new hose. Replaced the hose and turned the water back on. The pressure surge of turning the water back on blew the ice maker supply line under the cabinets and started the flood. Secondary factor was the routing of the icemaker line behind the oven which was being used to bake some cookies when I turned on the water.
Pressure surge plus softened line from the heat transfer as well as lines that are ten years old and have quite possibly experienced both heat and pressure surges hundreds of times, equals failure. High line pressure and no regulator didn't help any either.
We all learn from experience, ours as well as others. Some of us are just slow learners.