You said the following:
". . . you need to look at your mistakes and see how severe they are and decide from there if you should move on."
My computation errors are small, mostly sign errors. For example, instead of x = 4, I write x = - 4 but I understand the general problem, the big picture.
You also said:
"Move on only after you master the section!"
1. I work 40 overnight hours. This means I sleep during the day. Monday is my Friday as I work Thursday through Monday. Working overnight hours is not even remotely the same as working during the day and/or the late afternoon, early night shift. Giving up my sleep time takes its toll on the body.
2. The only FULL DAY I have to take of personal errands (and somehow squeeze math into my schedule) is Tuesday.
3. I am off Tuesday and Wednesday. However, I go to bed at 2pm to start my Thursday morning shift Wednesday at midnight from 12am to 8am. Remember, the next day begins at midnight.
4. I took off this past Sunday into Monday morning (my Friday) because I had a podiatrist appointment at the VA Hospital.
5. I wish I could "master" every chapter/section but this is an impossibility based on 1 through 4 above (and other reasons). In other words, life often gets in the way.