"hire fast and fire fast" is great way if you are allowed to. But there are 2 huge impediments to this: legislation (for example in Europe) makes it very hard to fire, sometimes almost impossible and, in many companies, the hiring manager does not have the authority to simply fire someone, especially fast. You need to do PIP for months, involve HR, internal procedures, legal procedures, it is a nightmare.
There is a third, very egotistic reason: for many managers letting go of someone is considered a negative, so they avoid doing it. I saw cases when the direct manager of a very weak contractor took almost one year to be convinced to end the contract, he gave second, third and infinite chances to a lost cause. But this is a case of a bad manager, can be solved.
But when it can be done, it is great.
There is a third, very egotistic reason: for many managers letting go of someone is considered a negative, so they avoid doing it. I saw cases when the direct manager of a very weak contractor took almost one year to be convinced to end the contract, he gave second, third and infinite chances to a lost cause. But this is a case of a bad manager, can be solved.
But when it can be done, it is great.