Thank you In Freeze Mode, the flash duration can be as fast as 1/19,000 second and usually it is less output on the flash to create the super short flash duration . It is used in control environment usually to have a black out studio and lets say you throw some water in the air and you want to catch the water droplets in midair with freeze mode the flash will trigger at the shorter flash duration and you capture the water droplets sharp without motion trail. Because the only light in the scene is from the flash It freezes the motion . Without the freeze motion or 1/20000 of a second flash burst you get some motion on fast moving objects. The speed lights on the lower end of the power are around that speed and when you dial 1/4, 1/2,1/1 the flash duration get proportionally longer because they have ti pump more power in the flash to give more light and the lamp it takes longer to get from 0 to 1/1 because the lamp meeds more time to get that bright. In any other situations where is ambient light in the scene freeze mode its not doing anything . Its harder to find bigger strobes with fast flash duration in the 1/18000 range and up but small flashes are common . And it works only if your flashes are the only light source for the subject you photograph and you want the freeze some motion . Let me know if it makes sense what i said and please let me know if you have more questions Best regards

I found this on Profoto website - hopefully will help better . Check this link : profoto.com/int/profoto-stories/whats-different-when-youre-shooting-in-freeze-mode?gclid=CjwKCAjwseSoBhBXEiwA9iZtxhkhdniVzvod9_Q5gQaJ02Sj64r9Vvfm6Y3KtmPEi5_IVjNVPP9WnxoCtBIQAvD_BwE

I was shooting at f2.8, ISO 100 and shutter was 1/100 because i wanted to open up a little bit the background .