Theres no mention anywhere of it being compulsory to take a minimum of a year- indeed quite the opposite, it says UP TO 12 MONTHS.
On introducing the new measure the authorities also stressed it would specifically be helpful for those with holiday homes who take longer vacations, so again NOT aimed at f/t residents.
UP TO. 12 months surely would imply 5,6,7 months
A possible explanation-You can take a Short Term RP for 5, 6,7,8 months etc BUT if for example you took it for 11 but went home after a month, come 4 months of absence from Turkey it would be cancelled requiring you to apply over again.
In other words apply just for what you need be it 4, 5,6,7 ..up to 12 months.