Find the strongest observed weekday for published posts.

Uses posts published on the requested calendar dates in the authenticated user's timezone and each post's latest available metrics. A zero engagement rate is measured only with a positive denominator. The weekday with the highest average per-post engagement rate returns ready with at least three measured posts on that day, three across other days, a 10% relative lift, and a 0.5 percentage-point absolute lift over the pooled other-day average, with no tie for first place. If either post-count minimum is not met, measured posts on at least two different weekdays can return early_result with the same lift and no-tie checks. Only weekdays with measured posts are compared. Early results describe the selected period and do not guarantee future performance. Empty accounts uses all owned and Analytics-permitted shared accounts in the selected team or workspace, including disconnected accounts with historical data; one account returns account scope, and multiple accounts are pooled per post. Requests are limited to 200 days and 25,000 matching posts.