From my experience working on the L1011, it used subtle attitude changes to correct small speed variations, as that was more efficient that constantly adjusting the throttle.
When you consider that the RB211 LP fan set weighs a tonne (or therabouts) plus the mass of the compressor and turbine, you are trying to accelerate a large mass for several seconds before the extra thrust takes effect, only to bleed that off again shortly afterwards. Now multiply that by three to get the whole aircraft effect...
Engines also have 'sweet spots' and work best for their intended cruising speed and altitude. They always suffer in the AAR role which is generally conducted below 25,000 feet since the fighters couldn't get much higher with long range tanks on...