It was my post in the other thread that prompted your question!
I used that quote in the context of what I was saying in my thread. Both the friend I was quoting and myself come from a military flying background before joining NATS. The military, like NATS, stipulates how many hours a course will last for. There is some leeway in this for students who are deemed to be 'almost there'. However after a certain amount of time you have to say enough is enough and stop training.
Civilain pilots who have enough money can spend as many hours as they want to obtain their licence... however a pilot will find it very difficult to gain employment if it is known that he had to take an inordinate amount of hours and re-sits to pass his tests.
If you had an infinite amount of time, it is feasible that you could train almost anyone to become an ATCO (the same is true of any profession). The exam to get your licence is held over one day so if their is nothing unusual going on, then you could pass it with thousands of hours under your belt.
However, the reason we have stipulated number of hours is because there has to be an element of being able to adapt to situations you have never seen before... as long as during those 400 hours you have seen the range of situations required under the Unit Training Plan (and dealt with them) then you will be put up for your Board (final exam).
The 400 hours have to consist of the right level of traffic - starting of with dealing with quiet traffic, and getting busier as you progress. When a daily report is written on you, the level of traffic is noted - you will not be allowed to validate if you have not worked busy traffic (relative to your unit), even if you have done 400 hours.
Some units require less than 400 hours, certain sectors at LACCC allow 500 hours as the normal. During those hours you will be given daily reports and then every 50 odd hours a level check which you have to pass before progressing onto the next 50 hours.
The question 'could anyone become an ATCO if you gave them infinite hours' is realy a moot one, as infinite never ends, so you would never know!!
There are limits to amount of hours allowed for very good reasons.