[hannes69]

What? Do you have a source for this, an explanation?

There are two clocks running independently - the video clock and the audio clock. Reference clock is the audio clock. If both clocks are in sync (could be by accident but is normally not the case), perfect refresh rate would be a multiple of the frame rate. So for non-europe movies (24 / 1.001) * n Hz e.g (24 / 1.001) * 2 Hz = 47.95204795 Hz. For the real situation of non-sync clocks things change.
I take my computer as example. Madvr shows the clock deviation between the audio clock and the video clock (this is not changeable!). The value stabilizes after a 15 minutes playback of a movie (it takes some time due to the measurement method). In my case I have a clock deviation of -0.0026%, that´s -26ppm (parts per million) meaning the video clock is running 0.0026 % too slow in regards to the audio = reference clock. That means: In order to not have dropped or repated frames I have NOT to use the refresh rate of 47.95204795 Hz from above but a refresh rate of (1 - 0.0026%) * 47.95204795 Hz = 47.9508012Hz.
The factor is for all different framerates the same, so for e.g 29,97fps: 29,97 * (1 - 0.0026 %) * 2 = 59.93844156 Hz.
With CRU utility one can define custom resolutions to get VERY close to these calculated refresh rates.
In my case I have refresh rates for 23.976 / 24.000 / 25.000 / 29.970 fps movies exactly enough to have no single frame drop or repeat within 3 hours.

so you should try to get the clock deviation in madVR as low as possible without aiming at 24000/1001.

Surely you meant the right thing but used the wrong term. You can´t change the clock deviation, but you can change the video refresh rate in order to compensate for the clock deviation, see above.