No, but the program should internally track each actual assignment served by each resident/fellow (regardless of the number of days, weeks, or months of each assignment).
The block diagram is often confused with the resident/fellow rotation schedule. The block diagram is a map of the planned rotations (or other educational experiences) for all residents/fellows in a given post-gradaute year. A rotation schedule depicts the actual sequence of rotations (or other educational experiences) for each individual resident/fellow. The ACGME requires programs to annually submit a block diagram but requests submission of rotation schedules only rarely and for very specific reasons. Refer to the Residency/Fellowship Program Directors’ Guide for further clarification.
Residency Program Directors' Guide: pages 82-89
Fellowship Program Directors' Guide: pages 74-79