I feel for you all! I’m also someone who works super hard, but then has very little to show for it. This is my 11th year at University (I have currently two Bachelor degrees and am working on my Master thesis) and I have struggled for all of those years with balancing life’s responsibilities (work, study, home, relationships etc.).
This year my grades for the first time in years are good overall. Before that I barely passed difficult or boring subjects while doing well in subjects I found more easy or more interesting. But that’s typical I think.
I found that building some groundwork first helps with every subject, but especially the difficult / boring ones. My brain needs some kind of ‘coat rack’ so when I’m studying I know where in my mind to file certain concepts. I would make some sort of mindmap for every week or lecture with the topics covered in that lecture. For example if I would need to know If someone was entitled to compensation (I study law) or who was the owner of a certain item I would write down the question (owner?), the categories or problems and how to solve the case when those problems occurred. So problem x solve with legislation y or case z. At that time I might not remember yet what legislation y or case z said in detail, but when I studied everything I knew exactly in which box to place it in my mind (so to speak). This saves me a lot of time, because my studying is more effective + I use the mindmap to quiz myself regularly.
What helps is asking other students what they do to prepare for tests. I used to make my own summaries because I thought that only I could make them perfect, but have since learned that I save a lot of time if I just buy one from some other student. Even if that summary is only like 75% good, the time you saved by not making your own summary gives you time to really know and understand almost everything of it. While making your own summaries (at least in my case) left me with no time to actually study them. Also class notes are everything. In my experience the majority of test questions reflect material covered in lectures. So leaving space between your notes and completing them with what’s in your textbook is also a good way to get good grades.
I find it difficult, but I now keep saying to myself that it does not matter if I’ve covered the whole textbook if I do not remember anything of it. It’s better to prioritize the topics that are actually covered in class and know them by heart.
I wish you the best!