Salutary, by definition, means: <em>"producing good effects; beneficial." </em>and it can also mean: <em>"health-giving."</em>
So, salutary is a positive effect. When associated in vacation, it is based on the idea that it is healthy and beneficial for the employee to take a break from work. That because that employee will be much happier with some time to rest and will most likely come back more productive than when he left.