Have you calculated what rarely using that apartment costs you?I was waiting to see what they would announce in the budget but having seen the incentives I will either sell or leave the place empty.
From a purely financial perspective, choosing to sit on an asset such as that which costs money to maintain is the domain of the wealthy and that cohort tend to need a very significant financial incentive to forego little luxuries such as a bolt-hole away form home for occasional use. Selling it, investing the proceeds and using the income generated from that to rent accommodation where and when you want it makes a lot more sense.