It is possible that  at 12:00 pm a person was located in a city and at 3:00 pm he was identified in another city (geo.city in target). He was connected by 4G.

It is possible that their IP can change. Adobe takes their IP and map it to a geo that is provided by geo-targeting vendor, Digital Element. The user’s ISP changed their IP address at some point.

Mobile device geotargeting on 4G, LTE, etc.  is less reliable than standard internet  (Cable, Fiber, etc.)

See from Digital Element’s accuracy FAQ here: https://www.digitalelement.com/resources/faq/

Yes. Generally, Internet traffic can be broken down by connectivity type into:

1) Wired PC-based traffic

2) WiFi-based mobile-device and PC traffic and

3) Cell tower-based mobile device traffic.

IP geolocation data will enable you to accurately target the first two connectivity types – fixed and Wi-Fi. In terms of traffic from mobile devices specifically, Wi-Fi connections represent well over 80 percent of mobile Internet device traffic in terms of how users are connecting, meaning most mobile device traffic can be accurately targeted using IP geolocation.