I recently finished up a Princton with a 21j twin barrel Slava 2414 movement and wanted to see how long it would go.
I did 2 sets of full wind time tests and here is what I came up with.
Tests were done flat on back with no moving.
Test 1 took 56 winds and produced 53 hours and 32 minutes with +6 seconds accuracy.
Test 2 took 54 winds and produced 54 hours and 5 minutes with +5 seconds accuracy.
The winds are what I would call average and may not be full 360 degree turns.
I am in process of one final test that will give me a good overall average and it took 56 winds. I am happy with the accuracy and duration.