Separate the commercial terms from the site schedules
The mistake in multi-site buying is trying to make the buildings the same. They are not. A civic building, a clinic and a suburban office have genuinely different cleaning requirements and pretending otherwise produces a schedule that suits none of them. What can be made consistent is everything around the schedule: how work is priced, who supplies consumables, what reporting is provided, how variations are approved and when reviews happen.
Write that as a head document, then attach a site schedule for each premises. The head document is negotiated once and rarely changes. The site schedules are living documents that can be adjusted as individual buildings change, without reopening the commercial arrangement. This structure also makes adding a seventh site straightforward, since only the schedule is new. Reviewing the head document every couple of years is enough, provided the site schedules are kept current between times.
