The thirty-first day of the month in the 6Year Plan is for reflection. Review what you have read thus far. Meditate on what God has revealed to you. Ask yourself how God wants you to put His Word into action.
The 6Year Plan is designed so that every Bible passage is seen on two consecutive days. The first day is presented in the ESV translation and meant to be studied on that day. The second day, the same passage is presented in one of several translations. The second day is meant for reflection on that passage. Similarly, the thirty-first day allows you to reflect on all that has been read.