Self-plagiarism came up in my program last semester and the professor’s position was harder to argue with than I expected.
My initial take: you wrote it, you own it. Submitting your own previous work shouldn’t be plagiarism.
Her counter: academic work is meant to demonstrate new learning. Submitting the same project across two courses doesn’t demonstrate learning for both courses, regardless of who owns the work.
I think the honest answer is: context matters. Using design work created for one brief as a portfolio sample in another course is probably fine. Submitting the same written analysis or case study for two different courses with different learning objectives is probably not fine, even if the work is yours.
The grey area: revising and significantly expanding previous work. At what point does an update become a new piece? I don’t think there’s a clear line.
What’s your institution’s actual policy and does it distinguish between visual and written work? Most of the discussions I’ve found online focus on written work and don’t address design specifically.