The correct answer is: Application of learned skills to the job

Rationale: On-the-job approaches support 'transfer of learning': skills are learned in the actual context in which they will be applied - so application is seamless.

Ability of learners to concentrate on the learning process and risk of errors are advantages of off-the-job training: the learners don't have the distraction of other work duties, and errors while learning are less likely to have real consequences.

You may have hesitated over relevance to the informal customs and practices of the department, but there is a risk that by learning on the job, people will pick up 'bad habits' and short-cuts - rather than best practice.