Local incident here yesterday, man struck by bucket that fell off hoe, pin grabber quick attach. http://globalnews.ca/news/2642276/calgary-man-struck-by-track-hoe-bucket-while-working-in-trench/ .
Quote from article "Crews had to shore up the trench before they could enter." I guess if you are comfortable being under any load why would one worry if the trench would cave in. With todays quik tach buckets its just one more thing to go wrong if you take safety shortcuts.