When are parts of the works not defined within a section to be completed earlier than the whole works to be completed?

NEC3 and NEC4 Contracts Secondary X, W and Y options
1

When are parts of the works which are not defined within a section that is to be completed earlier than the whole works to be completed?

2

Any parts of the works that are not defined within a section are required to be complete when the whole works is complete.