Maybe for tax purposes. However, and I am not expert, I would think that the unit must at all times have an owner. The earlier owner is a member of the Owners Corporation until the moment the newer owner becomes a member of the Owners Corporation. So, when does the name on the title change? Isn’t that at settlement?
From a real estate site: “Property settlement is the legal process that is undertaken to transfer the ownership of a property to another person during a sale. … Both sets of representatives will sign all the necessary paperwork and then it will be forwarded to the respective title office in your state or territory. The day of the property settlement is also the day you receive the balance of the payment from the purchaser, and the sale is subsequently finalised to completion.”