It's not even that strict. In Denmark you have to have been a resident continually for 9 years, with no long periods of travel abroad, before you can even apply for citizenship, as well as a 'permanent residence' permit.
You also have to have been employed continually for 3½ of the previous 4 years, have a clean criminal record, as well as pass several Danish exams and a citizenship test where you must demonstrate knowledge of Danish society, culture, history and so on.
After that, you have to participate in a ceremony where you shake hands with the mayor or alderman of your municipality, sign a declaration where you swear to comply with the Constiturion, respect Danish values and laws, and support democracy.
THEN your name is added to a formal law which must be passed by the parliament - as Danish citizenship is awarded by law.
Så står den vel på dødsdruk og en tur på den Sidste?