Most of the time clock drifts and time-stamp discrepancies are related to illegal activities. It's a massive network using atomic-clock monitoring throughout the whole system. All synchronized with one time source. It uses a wide variety of software to prove accuracy across the board. Logging every event and analyzing the whole for drifting. Some systems have low cost battery base quartz crystal clocks. These tend to lag behind the time protocol. Plus, there's the satellite GPS systems. These are vulnerable to signal disruptions over the wireless. Leaving wormholes in time for secret and active travel across the framework.