True. All that matters is the operator does his or her due diligence. I was being sort of facetious about chain stretch but there is a limit. It's 5% but I can't recall what length you are supposed to check.Good point! Hard to know if the links deform under load, or whether the links move relative to each other as tension is applied to the chain, or a combination of the two. I don't think there's a right or wrong answer here as long as whatever is used is able to keep the load secured and on the trailer. The rest is personal preference perhaps based more on factors unrelated to the load in question.
Here's an interesting reference for those of us that use chains. I use Grade 70 chains but Grade 80 are available too.
Welded Grade 70 transport chain allows a greater strength-to-weight ratio meaning lower costs and a lighter chain, for easier storage and handling.industrialrope.com