3) If it will not work then your planning or controlling has gone wrong.
That has to be one of those statements which prove that some of those without the yellow peril simply do not understand the big picture.
We plan, we execute but we also rely on other factors not least pilots, with the best will in the world plans go wrong they do not mean that either the plan or the ATCO was incorrect. The difference between someone who thinks they know and ATCOs who do the job is that they are able to continuously amend their plans. Every action we take impacts on the overall plan, one word in from someone unexpected, quite often a feature on either a Tower frequency and on LARS, means that an instruction gets delayed and thus what would have worked very nicely thank you now doesn't.
The worst critic of an ATCO is the individual themselves, they will think about the situation they created and how they could have dealt with it better and by that learn. Competence is constantly assessed ,although a yearly examination takes place should an ATCO fail to maintain competence within that year they will be subjected to either further training or have their licence pulled, a situation I know many of us who have controlled LARS wish could happen to some GA pilots.