In fact, judging whether the teacher's level is reliable depends on whether he is an on-the-job civil servant. It's no use. There are too many civil servants on the job, and the examiner has little to do with the level of lectures. When you review for a period of time, you will find that the answers to interview questions are very scarce. Many websites or remedial classes only put real questions to attract traffic and never write answers, because most people can't write them. For example, some teachers prepare a few questions and then only talk about these questions, which does not reflect the level.
I found that the content of mind map in official website was very good, and the recording of teacher Jiang's answer in Himalaya was of high quality. I recommend studying.