I might actually disagree on this one. If it was the first year of their PhD, then yes, it does seem like grunt work which is dissatisfying, but they will have fully learned the ins and outs of their group's code framework.
In the process, they would have understood nearly every approach taken by the group towards producing the results that it does, and I bet that has helped them when they've ended up modifying that same code later for their research. And with fewer supervisor meetings to work out exactly what X, Y and Z part of the code does because they will have worked on it themselves.
I'd say I've easily spent 6 months just spending time getting my head around all the code we work with anyway, so at the very least, I hope that made their following years of research more productive.
In the process, they would have understood nearly every approach taken by the group towards producing the results that it does, and I bet that has helped them when they've ended up modifying that same code later for their research. And with fewer supervisor meetings to work out exactly what X, Y and Z part of the code does because they will have worked on it themselves.
I'd say I've easily spent 6 months just spending time getting my head around all the code we work with anyway, so at the very least, I hope that made their following years of research more productive.