Why do readings change constantly?
Overview samples a running system. Applications and macOS continuously begin and finish work.
Why does another monitor show a different value?
Sampling intervals, units, interfaces, scope, and calculation methods differ.
Is high CPU always a problem?
No. Judge it against the workload and duration.
Is unused memory the goal?
No. macOS uses available memory for useful cache. Sustained pressure and symptoms matter more.
Why does disk space differ from Finder?
Purgeable data, snapshots, shared blocks, timing, and scope can differ.
Is the battery time estimate exact?
No. It changes with current workload and power use.
Does network activity identify an app?
No. Overview shows aggregate activity; use process-level tools for attribution.