I don't really understand how changing a movement can relieve stress on your body.
If you still push yourself to the same limit on the new exercise and as long as it is a similar exercise that delivers equal stresses i.e. bb bench - db bench you in fact by changing the exercise deliver more stress on your body by damaging your muscle fibers in a different altered movement due to the new exercise that helps break adaptation.
Even if you change exercises every week then still, from one exercise to the next the stress on the CNS be it from from an incline, decline or flat bench press is still stress on the CNS.
If i run forward until i fall down in exhaustion then next week i run backwards until i fall, i still place similar equal stress on my body at the time.
Maybe if you change a bench press to a fly you place less stress on your body due to the smaller amount of muscles being stimulated at one time, but what is the point in that? to me changing a flat bench to a decline is still placing very similar stresses on the body.
Altering intensity and or volume is by the far the most certain way to relive or increase stress on the CNS.