If a student is given a function on the calculator active section and told to find the x-value at which the absolute maximum occurs and that student does not test the candidates (end points and critical points), but instead draws a sketch of the graph, identifying that the endpoint is clearly the maximum value, does the student receive any credit?

The grading rubrics all show students checking the candidates, but I have a hard time explaining to students why it is not reasonable to simply look at the graph.