Thank you for you reply, Gábor.

The problem with adding such big residential areas is that it's no verifiable, which is one of the main pillars of OSM.
It's not a good practice and in Portugal we try to avoid them as much as possible for big urban areas.
Please, refer to the wiki for this very well know problem:
https://wiki.openstreetmap.org/wiki/Tag:landuse%3Dresidential#When_not_to_use

Regards,
António.