So I see this bad habit all the time.
You've conquered a grav , yet your ENTIRE fleet of strikecraft and frigates sit there watching a capship bomb the planet.
Now whilst this is happening..you have no idea whats in the neighbouring gravwells. You ever stop to think maybe you should leave the caps killing the planet and try to attack another grav well before the enemy can build up there.
Now you remember the AI. Remember all those times you spend killing him ...ONE...GRAV...AT...A...TIME.
Then suddenly out of nowhere a level 1 capship appears with a ton of cobalts. Why not send one carrier to kill the construction frigate before the shipyard is made that makes the cap!
Remember that the enemy is responding to you in some way. Just because nothing is happening at the planet your bombing doesnt mean they are not doing anything. They are infact probably setting up defences at their next grav.