What if you were shooting at 240fps; would you need 1/500? Unless I was going to want to rip out individual frames as stills that need a fast shutter speed, I'd use 1/320.
I used to think that you could get away with faster shutter speeds at higher frame rates, but after buying a 360fps laptop, I've found that you need blur for motion, even at that framerate. Any sharp edge that moves more than a couple of mm on the monitor between frames will appear as a multiple exposure. So, while 180 degrees seems to be a good compromise between stuttering and too much blur at 24fps or 30 or 60fps, that shutter angle is not going to be near-optimal over the entire range of potential framerates. For very low framerates, you are going to have a "fast slideshow" type of effect, anyway, so fluid motion is less expressable, and you may as well look at sharper "slides", and at the very fast framerates, there may be no utility in truncating exposure time at all, and rows of pixels should probably be reset immediately after they are read if the video is to be used as video, and not as a burst of intended stills packaged in a video file.
So let's say you had a 600fps video camera; you'd probably want to use ~1/600.01 exposure time, so that motion is as blurred as possible, and also, you'd have almost zero blackout at any pixel (just the read/reset interval), so you could resample the video temporally, without any temporal aliasing artifacts, or individual ghosted (multiple-exposure) frames in a slower-fps output.
