You don't need to mash parry from certian strings at all. I found an intresting method that is much easier than trying to mash. If you input any normal immediately after a IAC and follow up with a normal parry it will come out every time from multiple starters.
B33, F42, B12, 12, 11, 24 also works with this method
CONFIRMED: Cassie, Reptile, Sub-Zero, Kung Lao normal hat spin
DOES NOT WORK: Kung Lao Ex Spin in Tempest and Buzzsaw
I find this immensely easier and more consistent than mashing. Video soon.