... but than not.
Think as it as such:
Patek has made to the naked eye invisible 10 steps/sec moves of the chrono second hand visible by using another hand, that is directly linked to the chrono hands wheel, but rotates faster, because of the used ratio/gear.
Therefore it runs faster and smooth
(no 10 steps/sec anymore, which the grey, other chrono hand still does) over the dial.
Because it needs 12 sec/ rotation, it is perfectly matching the dial segmentation and very confortable for the naked eye now, to see 1/10th of a sec!
It is in essence simple š.