If an individual reads anything on a site like this and goes into an assessment and sprouts any of it verbatim without actually understanding the concept, they wont progress anyway as they will be picked up along the way in all manner of areas.
The post people are referring to is just talking aout concepts that a successful candidate would have to be aware of in the first place.
ATC is a rules based game. You are given a set of rules and you must follow them exactly every time.
Verbalise. Assessors are not mind readers and if you don't tell them what it is you are doing and why they don't know if you solved a problem by design or by accident. If you did not mean to do something, you can't be recognised as knowing you had to do so.
Workload and scanning. You have your basic rules as mentioned above. Everyone has their rules. Some of those rules are different between people but influence the required execution by others or yourself. Using your rules and educating and sharing those rules with others helps the whole operation. Assist others around you using your rules and theirs to maximise efficiency and spread workload. Constantly check (scan) your work and that of others to ensure accuracy and compliance. Relieve others of workload where appropriate while keeping vigilant about your own. This is the whole of ATC rolled up into one assessment without having to talk to a single aircraft.
ATC is change heavy. Be prepare for change, be aware of changes and be accepting of changes. ATC do not interpret change but implement and ensure compliance with change. If there is a change that is in conflict with your already known rules then say so but if it complies, even if you personaly don't like it, shut your mouth and implement it. Suggest alternatives but until they themselves become rules, operate as per procedure.
The above is a summary of the concepts contained in the post in question. Understanding these concepts will be a very good place to start not just in the assessment but as an ATC. It is not giving anyone an unfair advantage as some people will just 'get it' and will likely be successful anyway. Anyone just trying to parrot these concepts without understanding and application will be seen through quick smart anyway.
Best of luck to all. It really is a fantastic job.