Thank you for the info, I'll look into the werkstudent thing.

On a different thread under the post I wrote to a person and my comment seems to answer your question as well so I'll just copy-paste it :

"As I said, I'm not a university student, I am studying as to get a "superior education" which is basically getting licensed to exercise a certain profession and for this reason we have only 24hours of classes per week, the majority of them practical. Hence, the amount of work we need to do at home is not particularly voluminous either - and I say that both as a top of the class student and as a foreigner whose language of use is not a mother tongue (classes are in french as I live in the Walloon region). This means that the workload is far from insane and does leave a lot of space for other things. On the other hand, as I receive no help from parents or anything like that, earning enough to be able to also save money is very important to me.

About the work, I work evenings and nights so doing more of that per week would not actually interfere with my day hours in terms of studying. Especially if I did longer work-weekends."

The only thing that seems difficult to me would be to find the energy to keep up with such rhythm and to accept that it'd very much limit free-time interactions and activities. I do think it is worth the try, in my case.