should the kiai length be longer or stay the same?

...admit it you've all had that one song/sound that goes for 5.000000000000001 second and it doesn't work...

orrrrrrrrrrr

different length kiai item like 5 second 7 second and 10 second?

idk there just times off the top of my head soo... i know there has probably been about 69 million threads on this but yeah...