I have a problem with matrices

In matrix tests, I get through about half+ of the test, and then I often get too lazy to continue, so I start rushing to finish faster, without really focusing or thinking deeply. Even when I decide, 'Okay, now I’ll sit down and do it properly to find out my approximate exact level,' the same thing happens again. Right now, I’m also in a prolonged depression, which might be a factor or it could be something else. Even though my level is good, I still always feel like I could do better and go significantly further…

Has anyone experienced something similar?