A calendar turns posting from a daily scramble into a plan. It lets you spread pillars over the month, prepare for holidays and launches, and give reviewers time to approve.
A useful calendar shows more than dates: the status of each post, the channel and who is waiting on whom. Then a free slot on Thursday is visible before Thursday.
Example
A florist plans February two weeks ahead: Valentine's posts from the 7th, a delivery reminder on the 13th and a thank-you on the 15th.