<p>Visual literacy (VL) is a fundamental competency for arts students; nevertheless, its rigorous evaluation is a challenge due to the subjective nature of visual interpretation and the intricate interplay between visual and verbal competencies. Using the Common European Framework of Reference for Visual Literacy (CEFR-VL) to address this challenge, students identified a significant issue: the random distribution of the 16 subcompetencies in the original CEFR-VL visual model and the consequent difficulty in comprehending those subcompetencies. This mixed-methods case study reports on a trial performed to first examine how visual thinking activities during a series of diagram sketching sessions affected students’ abilities to recustomize the CEFR-VL visual model. Second, it explores how the revised CEFR-VL visual model improved the performance of arts students in achieving CEFR-VL subcompetencies and assists educators with their assessments. Initially, the students collectively restructured the CEFR‑VL model by recategorizing its subcompetencies into four functional channels through diagram sketching activities and guided inquiry. In the second phase, the efficacy of the modified model was evaluated with an experimental group and contrasted with a control group using the original CEFR-VL model. Qualitative evaluation and quantitative assessment showed that students who used the modified model performed markedly better in most subcompetencies. The results demonstrate that engaging students in visual thinking sessions enhances their VL subcompetency comprehension and reinforces a cohesive assessment framework. This case study promotes CEFR‑VL as a powerful customizable framework, providing practical implications for art educators and policymakers pursuing more innovative methodologies for VL assessment and associated challenges.</p>