The Tourbillon was invented in the 1700's to help with the accuracy of the mechanical movement technology of that time. By recreating it here, we are once again using old technology and then doing all we can with modern techniques to tweak / regulate it down to +/- 10 seconds per day. It would be unfair to compare a Tourbillon movement to a modern mechanical movement that has the benefit of 200+ years of innovation in accuracy, just like it would be unfair to compare a -4 to +6 COSC mechanical movement to a cheap $10 quartz movement or to an internet synchronized smartphone that keeps sync'ing to atomic clocks to keep up their accuracy.
In our actual documented use, over 1 month, we have observed the watch does not lose or gain more than 50 seconds.