If you talk to a lot of ex-law firm employees, they'll typically blame the firm, high billable-hour requirements, or lack of control over their calendars as reasons they failed at the firm (and yes, it is a failure). But in reality, many former law firm employees can more likely blame their own personalities for their failures, and not anything the firm did.
Law firm life is not for everyone. Everyone knows this. Some Harvard types can't cut it, while some community college grads make it to the top. What separates the two may have less to do with intelligence than it has to do with personality.
With that in mind, here are some common personality traits of law firm failures:
Oversensitive. If you have a tendency to turn inward when chided by a partner, senior associate, junior associate, secretary, or even a janitor, then a law firm may not be for you. Everyone will yell at you at some point during your first year, and these conversations will typically start with, "Can you close the door, please." Remember that if a partner takes the time to criticize you, the partner thinks you have some redeeming qualities. The associates being shown the door are usually the ones being ignored and sending out emails begging for work.
Lazy. You have to have a certain amount of drive to succeed at a law firm. Your drive may be that you want to do a good job so that you earn the big bucks, or simply a drive to prove that you're a good lawyer. Without that drive, you can get lazy. If you're more concerned about your weekend plans or getting out of the office by 6 p.m., law firm life may not be suitable for you.
Prideful. It's OK to be proud of your work, but don't be overly protective. Your winning brief may have won over a lot of judges in your own mind, but a more experienced partner will know how to craft the brief for the real world. Take edits in stride, and don't be afraid to give your opinion. But don't huff and puff if your suggestions are ignored.
Careless. This is closely related to laziness. You have to take the time and use some care in completing your assignments. This requires the ability to pay close attention to detail.
Arrogrant. You may think you know more than the partner assigning work to you. That would be your first mistake. While you may have researched some discrete nuance of the law more closely than anyone else in the office, you probably have no clue how to fit that piece of knowledge into any sort of meaningful advice.