Every few years a housing organisation buys a single source of truth. A warehouse is procured, pipelines are built, a launch is announced. Eighteen months later there are three versions of the void rate again. The tooling was never the problem. A single source of truth is not a place you build; it is a habit you keep.
The warehouse is necessary, not sufficient
A central model genuinely helps. It removes the worst duplication and gives people somewhere canonical to point at. But the moment one team needs a number the warehouse does not have, and needs it by Thursday, a spreadsheet appears, and the spreadsheet breeds. The warehouse did not fail. The governance around it did.
Definitions are the real asset
What makes a source single is not that the data sits in one database. It is that everyone agrees what each number means. The void rate is one number only if void has one definition that the warehouse, the board pack and the operational report all share. Modelling on a clean star schema keeps those definitions consistent, but the agreement itself is a human one.
Two reports built on the same warehouse with two different definitions of complete are not one source of truth. They are the old problem with better infrastructure.
Make the canonical path the easy path
People route around governance when governance is slower than the workaround. The habit holds when the central model is the fastest way to get a trustworthy number: when self-serve datasets exist, when new measures get added in days not quarters. Govern by making the right way the easy way, not by banning spreadsheets after the fact.
Buy the warehouse if you need it. But the single source of truth is the habit you keep the week after launch, and every week after that.