Originally Posted by Unregistered

I largely agree. Most big 4 teams I've seen are quite slow to drop trainees unless that person is really jialat.

Apart from things not really within the trainee's control (i.e. sufficient team billings to retain), reasons include:
- general incompetence, no common sense, carelessness (never check work against primary documents, assume this assume that without proper basis, etc)
- attitude (lazy, intentionally / recklessly slipshod work, entitled / stuck-up)
- bad 'fit' with the team (don't underestimate this)

Being a star performer in school but doesn't mean one is immune from the above.