The percentage Apple and Samsung show you is a smoothed, conservative estimate designed to reassure — not the granular truth of what’s happening inside your cell. The actual degradation lives in cycle counts, charging habits, and heat, and none of those show up on the screen you’re checking.
Deleting a file on a spinning disk leaves the data intact until something overwrites it. On an SSD, a quiet housekeeping command called TRIM erases those blocks in the background, often within seconds — which is why the old undelete playbook mostly fails on modern laptops.
