On-the-job training would typically improve skills needed in your day-to-day work. A master's programme should improve academic skills (things like abstraction,

On-the-job training would typically improve skills needed in your day-to-day work. A master's programme should improve academic skills (things like abstraction, reflection, generalisation, communication). The first makes you better at your current job, the latter makes you more flexible and versatile for any job. Both are valuable, but for different reasons. Whether pursuing a master's degree is worth it depends on your individual circumstances.