A watch is always more risky when there is no continuous time display (i.e retrograde hands or these jumping figures). Because in a pure mechanical point of view,the caliber has to handle the acceleration and the stop of the hour and minutes rings: this requires a lot of energy and also a system to protect it against a premature wear. Things are easier in apocket watch because you have more space to put a larger mainspring and complementory systems. In a wristwatch, it is a different story.
Fr.Xavier