How different in nuance?

1) The time required of “worker” to move from one job to another.

2) The time required of “a worker” to move from one job to another.

3) The time required of “workers” to move from one job to another.

Question

How different in nuance?

1) The time required of “worker” to move from one job to another.

2) The time required of “a worker” to move from one job to another.

3) The time required of “workers” to move from one job to another.

Answer

for a worker / for workers