I have seen both happen. Staff who have been on the job for a period of time know the processes and procedures and are better capable of getting the work done. I have also seen staff who have taken their employment for granted when management was not holding people accountable for their actions and performance. Once the first long time employee was let go for not fulfilling the job requirements, things started turning around.

Elaine Charest

I think there is a difference between Job securtiy in the sense that management would guarantee a certain level of stability for the employee through not resorting to downsizing as the primary option whenever there is financial issue and between taking one's job for granted as a result of not having an effective performance appraisal system that would reward doers, hardworkers and achievers and penalize others (of course based on clearly established criteria). In such a situation, employees will take their jobs for granted as it does not matter whether they did well or not, they will always be there and get their pay check at the end of the month.

A certain degree of job security is essential for productivity. Without this "psychological contract" an employee may not be able to grow their roots and not get invested in the organization.
Saqib Dara

I have a very nice employee at the present time. She is so relaxed that she does only half the work of people in similar positions. She is certainly taking her job for granted. I don't understand this philosophy when good jobs are becoming harder and harder to find.

Another way to look at this is some individuals are intrinsically motivated while others simply are not. Therefore, a motivated individual who is also experienced will therefore be very productive and most likely a true asset to the organization. However, an employee who is experienced but lacks motivation (for whatever reason) is not only unproductive in their own job, but probably negatively impacts other employees as well.