To support refurbishment use-cases a bit better, it would make sense to allow users to N/A activities directly from the mobile app. This could be a workflow:
Creation of standard template that includes all activities that potentially can be done per deliverable
Site walk to understand which activities actually need to be done per deliverable
Directly during that initial site walk N/A all activities that do not need to be done per deliverable using the mobile app
Afterwards sub-contractors can start executing the planned work