Broken stock springs are common. The manufacturers simply put too light-duty springs under RV trailers. You can beat the averages by installing heavier-than-stock leaf springs. That's what I did and had no more broken springs.
To do that, get the specs for your stock springs (length, width, thickness, and weight capacity). Find a good spring shop and ask them to build you a set of springs of the same length and width but about 25 percent more weight capacity. That should do the trick.Or maybe cheaper to surf the internet and find leaf springs of the right size and save a few bucks. For example if your trailer springs are 25.25" long and 1.75" wide with 2500 weight capacity (each spring pack), you can order springs that length and width with 3000, or 3625 pounds weight capacity.
Never reuse U-bolts. Buy new ones that will match the thickness of your new spring packs.
Grumpy ole man with over 50 years towing experience. Now my heaviest trailer is a 7,000-pound enclosed cargo trailer, RV is a 5,600 pound Skyline Nomad Joey 196S, and my tow vehicle is a 2012 F-150 EcoBoost SuperCrew.