It would be a foolhardy man who took the margins in the regs and decided they were all available for use "on demand".
I know of a christen eagle that is aerobatted to ultimate strengths because limit strengths are too tame.
the aeroplane has required substantial rebuilds and has almost structurally failed in flight a number of times.
I know, its a FAR23 aircraft not FAR25 but there really are pilots out there who don't really understand all their knowledge.