I think the issue isn't keeping the files but some riggers not taking their business and services seriously.
Knowing your client can only work with you, you should always be open to updates and have a flexible schedule to make them in a timely manner. Dissappearing, losing files or taking months for a tiny toggle is not acceptable.
If you can't garantee this basic customer service, you should find an alternative such as letting the client have the files when you're unable to continue with their project so you're not kidnapping their Vtuber model.
taking a very limited amount of floral and baking orders this month! iβm more inclined to bake if you order flowers alongside it but for returning customers iβm more than happy to work with you for events π«Ά feel free to dm!