"Special mask mode" in 8259A with OCW3 (PIC: Programmable Interrupt Controller)

The manual for 8259A says that

In special mask mode, when the mask bit is set to OCW1, it blocks further interrupts at this level and allows interruption from all other levels (both lower and higher levels) that are not masked.

Thus, any interrupt can be selectively activated by loading the mask register.

Does the operating system use this mode when the kernel configures the PIC? If not, lower priority interrupts will get slightly less benefit. Like a keyboard, it does more good than FDD. Whether the hardware interrupt mapping is a cascading PIC in a system assigned / hard-wired in order of importance.

Special mask mode or normal mask mode, which mode will have better performance or some benefit.

The proposal to implement the special mask mode when setting up the PIC for the x86 PC system will help me decide whether I should use it or not.