This answer to the question Apollo-11 delta-v “due to residual pressure in the docking tunnel pushing the spacecraft apart” detected as it happened? Was it corrected? quotes the following passage from the Apollo 11 Mission Report; MSC-00171
The third problem area was the large number of trajectory perturbation in revolutions 11 through 13 because of uncoupled attitude maneuvers, such as hot firing tests of the lunar module thrusters, undocking impulse, station-keeping activity, sublimator operation and possibly tunnel and cabin venting. The net effect of these perturbations was a sizeable down range miss.
Question: What are "uncoupled attitude maneuvers" and why do them?