Bram, once you squeegee the water from between the plate and film the film is well stuck to the plate.

You can do anything on film that you can with a stone, circles, half laps, X strokes. The film will not come off until you pull it off or it dries out.

It is a bit of a hassle, but it does work well and grits go to about 60k equivalent, though I prefer the 1um about 16k equivalent.

There are many threads and good videos on its use. It is just another tool, works well on very hard blades.

As said I often use a combination or just to finish. I did recently get a Gokuymo 20k that produce a similar edge to .3um film, without hassle, splash and go.