It all depends on the Network Buffer size on the client’s device.
Give this a read and anything @OttoKerner mentions about Network Buffer and Deep Analysis. And this thread too.
Remember, the Network Buffer allows for these fluctuations, and Plex’s Deep Analysis scans the file to see how the file will perform based on different sized buffers, (worst) 5/10/25/50/75/100/250/500MB (best).
Also, give the preset a go and test for yourself 
You might be suprised that it works.
