Many of us would probably prefer not to grade at all. But, in most cases, we do not have that option. You must decide how each element of your class is weighed in determining a student's final grade. For planning our courses, many of us have found the questions in Teacher Evaluations very helpful. Any aspect of the class that is optional, such as conferences that are not required, using the ALS, or carrying your books, should not be graded.
Writers can all improve and benefit, no matter at what skill level they start.
Some teachers weigh successive essays more heavily, to signify that improvement is expected or that the assignments increase in difficulty. Other teachers prefer to grade every essay and weigh them equally in order to impress their standards on the students and encourage them to be more serious about doing their best with each assignment. Some teachers only grade revisions. Some teachers grade each essay but do not write the grade on the essay itself, so that students are not distracted from reading the comments. A separate means of communicating grades is used.