AD9286 SPI control


We're trying to implement SPI control for AD9286 using a Virtex 5 FPGA. The data sheet says that FF reg. must be set to 01 for a write operation. We're setting 5 SPI registers. Must this FF<-01 be sent every single time before sending an SPI instruction or is it sufficient if we set FF register once during the start ?

Thank you,