Researching and writing your essay
will have consolidated your learning of the subject at hand. However,
the feedback you get from your lecturers can be used as further learning.
They might, for example, suggest new ideas, fresh examples or different
opinions. These are really worth considering while the ideas and arguments
are still fresh in your mind.
There may be simple corrections of facts or mistakes. Note these! There may be ideas on how you could express yourself more clearly or remarks about the detailed aspect of the structure of your essay. Study them all carefully.
The overall comment you receive will evaluate your essay as a whole, and probably involve some justification of the mark you receive. These comments have been thought through carefully and are designed to help you to improve your work - use them, don't waste them. You may get the opportunity to discuss your work with the marker: use this as a positive opportunity, especially if you haven't done as well as you expected, and build on what you learn.
It should be clear to you by now that essays are about a lot more than just covering a few sides of A4 paper. They are a vital part of your learning and it is up to you to maximise their usefulness to you.