Try fighting Titan without keeping Fracture, Demolish & ToD up at all times and watch your dps plummet(which is already low compared to ranged in that encounter). They are very worth using on anything with a large amount of health and it's easy to keep them up while maintaining GL3(though you need to be really on the ball),no way in hell it will have a high up time on primals but its managable enough to keep up until they perform their vanishing acts, GL3 that is.