1. Management gets benefit through increased efficiency and thus increased profit.
2. Worker is assured of a fair return for a fair day's work. He is protected from unfair demands. The work is made easier and more productive.
3. Trade union gets a reliable data measuring fair say's work and payment through work study. This enables trade unions to do 4. more objectives negotiations with the management based on factual evidence.
4. Productivity through work-study enables a greater amount of products and services to optimum quality and lower prices. So the consumers are benefited.
See this image: https://2.bp.blogspot.com/-YhzfRF2blvw/WTPluY2CJxI/AAAAAAAAgPk/O82ls9qJ1MQte5n3nN5QJJQjS897Fin4ACLcB/s1600/work%2Bstudy-min.jpg