Every week has surprises — a task runs long, a meeting appears, life happens. A mid-week buffer prevents the whole plan from collapsing when Monday or Tuesday overruns.
Great — use the extra time to get ahead on next week's goal, or invest it in analytics review and content batching, which rarely get dedicated time otherwise.
This plan intentionally excludes weekends to protect rest. If you must work weekends, treat that time as a second buffer, not core planned hours.