Many times a company will send you home after putting in your 2 weeks anyway. It is a wasted 2 weeks for everyone.
They typically cause more harm than good on the way out. I've investigated so many company theft cases it's insane. I always get amazed by how crazy people are when they decide to leave; stealing intellectual property and deleting/corrupting archives of information, just because they are salty. And it does no harm if the company is setup properly. Watched a guy steal all our data and start his own company a month later, he was wrapped up in lawsuits so hard he left the state.
A large company I worked for a few years ago would hire 3 people at a time for technical roles. Got rid of two of them before the 90 probationary period was over. No bonus or stock options until you made it a full year. Once you hit 5 years you get a door opened to almost unreasonable options and salary.
The trouble was making it 5 years. It was the most intense environment I ever worked in and very toxic. But working there for 5-10 years could change your life completely. And once other companies knew you worked there for a long stint, they knew you were a winner and offered you a nice high paying job.
I hired and fired so many good talented people I'm numb to it now, I can fire a good quality engineer without batting an eye. But a good talented person will be successful anywhere, they just need an opportunity to succeed, so it's not like they are out on the street. It's the losers that don't make it in corporate America.
Which is exactly why these large corporations run the way they do and make the profits they do.
Feed the machine.