thanks for sharing, abang shahir. good article. nothing new for those of us who're seriously into our watch hobby, even for a few years.
in any case, the quest for accuracy in time tracking goes beyond vph. atomic clocks in this regard will outperform quartz.
there's also "equation of time" if we're really ocd about the need to take the slight wobble of planetary motion into consideration.
heck, if we really want to geek out, gravity also has an influence on the speed of light depending on where the observer is. and this has a material and measurable though minuscule impact on timekeeping devices.
which is why GPS satellite clocks correct for this phenomenon in order to provide accurate tracking functions.
I enjoy reading write ups concerning watches and I would like to share this with you (I'm sure most would know this already

)
http://nickhacko.blogspot.sg/2017/03/what-is-horology-and-what-is-it-not.html?m=1
Here is an except..
"
To put it very simply, when we talk about horology, we talk about two things: 1. the chase for perfection in timekeeping and 2. the art of watchmaking. The quest for "the best timekeeper" is really a matter of progress, science, technical advancement and some extremely clever engineering.
Therefore, if you wish to enhance your appreciation for that first side of horology – the quest for PRECISION AND ACCURACY, you should sell your Rolex and Patek and buy a Japanese HAQ [High Accuracy Quartz] watch. My personal recommendation: Citizen CTQ57 Chronomaster or Grand Seiko 9F series. You can walk around knowing you have one of the most accurate wrist watches that still contains mechanical parts.... "