How shared areas fall between two arrangements
Each tenant's cleaning scope was written from their own tenancy outwards, and the shared amenity sits at the edge of both. Neither scope mentions it explicitly, both parties assume it is covered, and the cleaner from each side works to their own list. The amenity is then serviced by whichever cleaner is most conscientious, and stops being serviced at all when that person leaves. Nobody decided that outcome, and nobody is in a position to notice it until it has run for months.
The failure is slow and it produces disproportionate irritation, because a shared amenity is used by everybody and is the most visible indicator of how a building is run. By the time it is raised, both tenants believe they have been paying for it, and establishing who actually has been is an awkward conversation that a single line in a scope would have prevented. One line in a scope at the outset prevents an entire category of dispute later.
