Just because they are general they are not useless.
Where the article fails I think is that it takes intelligence to know whether you are giving up too early or not giving up too early. Also, an intelligent person would know or realise at some point whether they are spreading themselves too thin or thick, and do something about it. That is afteral what intelligence is for. Others however might not.Thus the people the article is speaking of seem to be perhaps not that intelligence. Thus "intelligent people" should be taken off the title as it applies more to all people.
* Giving up too easily or not giving up to easily
* Too little confidence or too much confidence
* Spreading oneself too thin or thick
* Taking too much blame or not taking too much blame
The problem being that there's no way to know (for example) if you're being too confident or not confident enough.