But what will the effect (on water) look like??? With enough exposures, it ends up looking murky, as there's only chopped (short) exposures, not enough time to build up proper (normal) highlights, and not enough collective "frames" to have a completed event image... With many exposures, it might start looking like a time exposure, as snapped elements start to join... Or something murky with something foggy over it...

You might as well just get a heavy ND filter, as exposure + reciprocity are easily calculated, as one of the benefits is that in a body of moving water, different flow patterns tend to replicate, so with a long enough exposure, the patterns emerge and become visible...

Actually doing some real tests reveal what the camera/film image "sees", rather than what we (think we) "want"... And do we like what we get???

Test, test, test...

Steve K