The fact that you have A grades on all your essays shows that you are an exemplary writer. . . . Once you're a really great writer it's difficult to make incremental improvements. Think of runners or swimmers who try to "shave" their times once they're in the elite ranks. :-) Yes, it's dramatically impressive when students make dramatic improvements -- and I wrote notes of congratulation to several who went from low B or high C grades early on to high B or low A grades by the end. They need to be encouraged about their strides. You just need the encouragement that you're continuing to do a great job, as you have from the start. You came into the course well equipped to do what we were looking for, and you have gone out of the course continuing to do it very well.Bottom line: it's just about impossible to score a 100, and a 95 is rare -- because we writing teachers want to encourage students to keep pushing for excellence and beauty. However, we should do what we can to structure the grades in a course so that students can succeed with their final grades even if their writing is not the best of what they do. In Composition 2 at Veritas Press Scholars Academy, essays count as 40% of the grade, exams as 20%, and participation and homework as 20% each. The participation and homework grades are "faithfulness grades"* that allow even struggling writers to succeed in the class.
All run the race, and all can finish well, but the ones who have "Olympic potential" will get more vigorous coaching to that end, not just a grin and a pat on the back.
*Thanks to husband Glenn Marsch, physics professor at Grove City College, for this concept.
Related: Jack Lynch: "Getting an A on an English Paper"