for me, the dialogue is visible as soon as the first flash starts to fade (i don't get to see it appear). the second flash is quite some time after... i would say as long as it takes for the first flash to fade away. the second flash is a single frame, no fading.
for me, the dialogue is visible as soon as the first flash starts to fade (i don't get to see it appear). the second flash is quite some time after... i would say as long as it takes for the first flash to fade away. the second flash is a single frame, no fading.