How is travel within the Schengen area actually tracked between countries?
A person is living in Portugal on a residency category where they are only allowed to stay outside Portugal for 4 months per year. They want to explore Europe by traveling across Schengen land borders (Spain, France, etc.) and are wondering how movement inside Schengen is practically tracked between countries.
Since many internal Schengen borders have minimal checks, how do authorities usually determine how long someone has been outside their country of residence? Is it mainly passport scans, transport records, hotel records, tax activity, mobile data, or something else?
The question is more about understanding how Schengen movement, geography, and interconnected systems work in practice rather than asking for illegal advice, he/she wants to travel and spend time in different european countries and experience it without being tracked on that 4 months limit. He/She can follow a land crossing border plan as well, like from portugal to spain its fine, then how he/she should be travelling across to other countries