Darn, I know I have read the 6 months item if seeking work - but I did check EU law and sure enough it's not there ( that I can find now ) - useful link if anyone bored : https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02004L0038-20110616
However ..... Dario , you have conflated the Schengen issue for non eu citizens which does NOT apply to EU citizens ( this sadly I know too much about ) "90 in 180" does NOT apply to EU citizens.
So I will bow to your 3 months and registration required ( colloquially called "residencia" ) until or if I can support my 6 month argument :-)
So 50/50 I'd say !
Cheers
:-)