In article , Carlos E.R.
wrote:

My old SLR had 1/2000

The mechanics had a trick that allowed high effective shutter speed
while the shutter in fact moved relatively slowly, at 1/60 or
thereabouts. And old trick, actually. It opened a slit on the rectangle,
and the slit travelled the length of the aperture. If the slit was 1/5,
the effective speed was the actual speed multiplied by 5.

that's not a trick, but how focal plane shutters work.

the speed at which the slit is the same size or larger than the film
frame in the dimension the shutter is traveling is the flash sync
speed, typically in the 1/60-1/250 range.

as always, there are exceptions. some digital slrs have a focal plane
shutter that can sync at any shutter speed.