Caltrac operation on leaf springs

Ok never had them and just curious about them working. What I know is that it is basically an adjustable bar that bolts from U bolt seat to front shackle that locks up preventing the axle wrapping up and trying to walk over the diff housing in racing situations. My question is do they then affectively stop the rear shackle from any forward movement if they are adjusted tight/preloaded. If it tightens everything up in the rear springs wouldnt you negate everything the spring does to give you a smooth ride when not racing. Is it something you constantly adjust to the ride you want.