What common mistake do developers make with Disks, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Disks, why does the mistake cause problems, and what is the safer approach? One recurring problem with disks is applying it without understanding the boundary it protects. Saving user uploads directly under a public web directory without validating file type, name and access requirements. In addition, Storage disks describe where files are stored and how the filesystem adapter should access them. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.