There are differing points of view on whether or not it is safe practice to trust a single bolt. I don’t think anyone would argue that you are absolutely safer being clipped in to two or more points than you are when only clipped to a single point. That said, many areas around the world use single bolt anchors and rarely see any catastrophic failures, however it should be pointed out that it only takes one botched install, only one mistake or case of forgetfulness or haste, only one un-educated installer to lead to disaster! As shown in the video below, what was a seemingly bomber bolt was far from it. Let this be a reminder to us all, always try to be clipped into two or more points. You just never know, even those with years of experience would be unlikely to realize the impending disaster that could have occurred had someone really tested this bolt!