Today I got me a self-timer the working of which I do not fully understand.

I could not find any image of it on the net. The closest resemblance (most probably the same manufacturer) has this one:

Mine is more elongated. It has two markings on the wind-up scale.
They set two different strokes of the release bolt. There are no intermediate strokes.
Intermediate positions on the wind-up scale will only effect the retarding of release.

"G"= 7.5mm

"P" = 15mm

I guess those markings refer to Gauthier and Prontor shutters.

Do they really need different strokes for release? Are these strokes fit?

(There is a thread to adjust how far the bolt runs down into the shutter, but there is no counter-nut and such this Feature is of not much value.)