It is much like a honeymoon period when a new employee  begins with the company; they need some kind of introduction to the business and a tour of the office.  A new employee will also probably need new office furniture and stationery and a certain amount of time invested with them to get them up to speed.

It is during the honeymoon period that both sides need to ascertain whether they are a good "fit", for both parties involved it is preferable that the new career move works out well.
Virtually 100% of new employees begin a new career or job with hope and inspiration wanting to make a positive impact to the company.

However, there are a number of reasons why things may not work out:

Wrongly recruited. This may mean that you were a little desperate to get someone in to help the cause of the business and you mistakenly made a rash decision grabbing the first person who looked half decent for the role.

Unclear reporting lines. If an employee is not clear on the reporting procedure they could find themselves torn between many managers trying to complete tasks they should be doing.

Changing work boundaries. A person hired for a certain position is dragged into different duties just after they started.