There are occasions when a division may fill and a few unplaced recruits remain. Those "leftover" recruits will be placed as the first recruits for the following division. There are also times that a division is not quite filled with the normal 88 recruits and that division must wait for the next group arriving in Great Lakes to fill to division compliment. When a division is held waiting to fill the division with the next group of arriving recruits, they will placed in what is called a PUSH Division.
Because that division formed "late" it is composed of recruits arriving typically over two different weeks. Some of the recruits in that division will be at RTC for 7 1/2 weeks (8 Fridays) rather than the typical 8 1/2 weeks (9 Fridays) that most of the divisions in that TG (Training Group). To stay current with the projected PIR date for the TG, that division is "pushed" thru some accelerated training- hence the term PUSH division.
This may happen more often for those recruits arriving at the beginning of a week. Recruits who are unlucky enough to be held over may be placed in a TG for the following week. These recruits are at RTC 9 1/2 weeks (10 Fridays). That happens more frequently for recruits arriving at the end of the week. This happens more around holidays or when there is a week without a PIR. Weather or severe storms may result in extra recruits being shipped to RTC when others are delayed. This may also occur if a large number of recruits are shipped to RTC in the summer and early fall due to enlistments that happen during a high school student's senior year.