英语作文is a training class or tutor necessary

Is A Training Class or Tutor Necessary?
Many high school students attend a training class or have a tutor.They go to a training class or are taught by their tutors during weekends.It's true that a training class or a tutor can be helpful for a student.Hower,as a matter of fact,I don't think they are necessary.The reasons are as follows.First,students can grasp all the knowledge in their normal classes as long as they put their heart into it.Second,if a student can't do well in class,how can they in a training class?