A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2016 Nov 4, 15:58 -0700
On all my computers I use NTP client software to synchronise their system time. This guarantees an offset less that 0.1 sec and eliminates the long-term drift completely.
As to why your G-Shock could "jump" its' time - I'd suspect the low-power condition or ageing battery element.