Second, checking for errors is always more time-consuming. That is to say, although you set aside half an hour to check, the errors detected in this half an hour are very limited, and more are wasted on unnecessary topics. And because you have just finished the problem, there will probably still be habitual mistakes when checking, so the mistakes can't be found out. I suggest you slow down when you do the problem and try to control your emotions. When calculating, if the calculated figures are "strange", on the one hand, you should keep confidence in yourself, on the other hand, you should look at the process carefully.
Third, the use of draft paper is closely related to the appearance of simple mistakes. I gave you this draft paper during the exam. If you make a draft at will, it may be more confusing. Arrange the use of draft paper reasonably to ensure that you can easily find the draft of the topic you want to check when you check.
Fourth, extend the time of reading the topic, see every point of the topic clearly, and don't flash by. It is very important that you always remind yourself that you can do the problem quickly and don't worry about the time. The important thing is to keep your mind calm and not be disturbed by the tense atmosphere.
Fifth, the focus of inspection should be on fill-in-the-blank questions and calculation questions, especially fill-in-the-blank questions. Generally speaking, you won't make mistakes easily when you answer multiple-choice questions (the key point is that your topic is understood correctly and not disturbed). You should be sensitive to error-prone questions. Generally speaking, the proof questions are not easily wrong, and the wrong questions are concentrated. When you look at the topic, recall the similar topics you have done before and think about whether you have missed anything. Also, it doesn't mean that you are wrong if the calculation is complicated. In fact, the general calculation is more complicated, but it is less likely that you can make mistakes. You should determine the problems you should check, and don't waste time.
The most important point you said is personal. The three examples you cited are very common. The key is to find out these points yourself and not to follow others easily. You can try to adjust your problem-solving situation according to the simulation paper of the college entrance examination. Don't think that you don't care if you make small mistakes in your usual practice, give yourself reasons. Any mistake is wrong, and mistakes need to be solved by practice. Practice arranging time in the exam, calm down, don't be eager for quick success, don't be impatient, and don't look down on simple things. You will find a solution.
I wish you success in the college entrance examination, come on!