Once I have checked the torque properly, I just check the torque versus re-torquing them. In other words, I don't loosen the nuts and then re-tighten. No need to really and I think it puts unneeded wear and tear on the components. Once a year or so is enough IMO but now you know that you do not have a stud pulling.
Sometimes the seats are too hard and the valve gives and sometimes it is the seat that gives. Very often it is a combination of both.