A dissertation is not simply an exercise in economics. It is also an exercise in personal management (part of the reason that job interviews often ask about it).
Departments are often very good at supporting students to carry out the economics ‘side’ of a dissertation: providing supervisors, and granting access to academic journals and statistical software for example.
But they often are less concerned with the personal management ‘side’ of a dissertation. This is with good reason – being a university student involves independent study, after all. Having said that, some universities have started to introduce intermediate deadlines for students. Even if this applies to you, you still might want to consider doing more work than the deadline requires depending on how your courses are spaced etc.
If your university doesn’t have formal intermediate deadlines, draw up some yourself at the start of the year with your supervisor. If you schedule regular meetings with them, where they check on your progress, then this will act as a commitment mechanism. This can make a big difference to the quality of the final piece (as students of behavioural economics know).